The inside story of the US election – and Barack Obama’s victorious strategy

In early spring, Obama’s veteran campaign staff in Chicago confronted the question that would ultimately determine the presidency: how to run against Mitt Romney? The choice discussed on frequent calls between the White House and One Prudential Plaza in Chicago was whether to campaign against Romney as a flip-flopper – a former centrist Governor of Massachusetts who turned conservative to win his party's nomination – or use his career as the head of Bain Capital to cast him as a protector of the privileged at the expense of the middle class.

"The most striking data we saw early on was on the 'understands problems of people like me' question," said a senior White House official involved in the discussions. "Into the summer, Romney was in the teens in this category."

The choice was made. The one-time campaign of hope and change soon began a sustained advertising assault that cast Romney as a heartless executive, a man who willingly fires people and is disconnected from how average Americans live their lives – an approach reinforced by Romney's mistakes along the way. While the Obama campaign bet it could set the campaign's course in the summer of 2012, Romney's senior staffers in Boston put their money on winning a decisive autumn, when it believed voters would tune in to the race in earnest and their "jobs first" message would convince the nation it was time for a change. But, as the attacks mounted, so did concern within the Romney camp.

"Ann would come to me and say, 'Eric, what are we going to do about this? It needs to be addressed,' " Eric Fehrnstrom, Romney's senior adviser, said, referring to the candidate's wife. Romney's family longed to tell the story of the "real Mitt", but advisers told them that the time for that would come later, during the convention and debates.

Another Romney adviser said: "The group think today is if we were to go back and change one thing, we'd spend more money and more strongly defend Mitt and push back on the 'rich guy', the tax-rate issue, the Bain Capital issue. We knew it was coming and we should've done more positive ads to get his favourables up." This account of how Obama won is based on more than two dozen interviews with campaign officials on both sides, advocacy groups and super PACs, and current and former White House officials. Obama advisers requested anonymity to speak candidly about the race in advance of election day. Several Romney advisers did the same.

Obama's decision to focus on Romney helped set an angry tone for the multibillion-dollar campaign, the first presidential race since the Citizens United decision changed the financial calculus of US elections.

But among the most critical elements of his success was the quiet work his staff accomplished last year in reviving and expanding a vast field organisation that lay dormant for much of Obama's presidency. The turnout on Tuesday of African Americans, Latinos, women, and young voters in swing states was a testament to its success.

Obama, weighed down by a poor economy, also needed help – and he often got it from Romney. The Republican's brash condemnation of Americans who do not pay federal income taxes, his quick criticism of the administration for a spike in Middle East violence, and even his selection of a running-mate that brought unexpected tension into the campaign all worked against his mid-autumn effort to surmount Obama's lead.

Amid an angry populism in the country, Obama's effort to portray Romney as a part of the economic problem resonated in the upper Midwest, where the race in many ways was cemented. In Ohio, Obama's early decision to bail out the car industry, and Romney's opposition to the plan, helped frame the contest in the incumbent's favour before it even began.

"He looked the part," a senior Obama campaign official said, "the Brylcreemed executive who comes into a town and asks why we're making Electrolux vacuums here when we can do it cheaper in China."

In the final stretch, Obama almost squandered his hard-won lead with a bewildering performance in his first debate with Romney. But, for a candidate whose political career has been touched at times by luck, Hurricane Sandy arrived with a week left in the race and disrupted Romney's effort.

The campaign bore almost no resemblance to the one Obama waged in 2008 – by strategic choice and by financial necessity. Without the clear financial advantage it had enjoyed last time, Obama's campaign relied more on the tools of micro-marketing than on the oratorical gifts of the nation's first black President.

Gone were the soaring speeches that clarified Obama's candidacy four years ago. Instead the President focused on Romney.

Before the effort to define Romney began, before they even knew for certain Romney would be the opponent, the Obama campaign laid the

In early spring, Barack Obama's veteran campaign staff in Chicago confronted the question that would ultimately determine the presidency: how to run against Mitt Romney? The choice discussed on frequent calls be groundwork for victory in a race that would be won in the margins of a polarised electorate. In January 2011, nearly two years before Obama would face voters, top strategist David Axelrod, campaign manager Jim Messina and other advisers moved from the White House to Chicago to be insulated from what one campaign official described as "Washington's chattering classes".

It was not an easy time in Washington. Republicans had just swept the midterm elections and retaken the House. The national unemployment rate was nearly two points higher than when Obama took office.

But what really worried the Chicago brain trust was money – the hundreds of millions they expected the Romney campaign and outside groups to spend on defeating the president.

The Karl Rove-led American Crossroads and affiliated Crossroads GPS, alone, said it would raise $300m (£189m) – a goal the group met, an official there said last week. Two-thirds of the funds were spent on the presidential race.

In 2011, something unexpected happened: nothing. The predicted Republican onslaught was largely absent, giving the campaign in Chicago the time and resources to set up the organisation a full year before the general election. The Obama campaign, on the other hand, spent $126m in 2011 – more than three times Romney's total that year. The campaign opened field offices, began an extensive effort in swing states and enriched a voter database with information unavailable in the last election.

Some of that expensive new data included viewer habits, collected by cable companies, that provided clues to voter traits and preferences. In a race where middle-class female voters were courted by both camps, the Obama campaign advertised heavily on the CBS's sitcom 2 Broke Girls, according to a Yahoo analysis of Federal Elections Commission data.

The tools allowed campaign officials to determine – on a house by house basis – how people were likely to vote and whether they were likely to vote at all. Voters were given "support" scores and "turnout" scores to tell the campaign's field offices who to go after and how. Field workers were fitted with mobile apps to give an instant report on every doorstep chat.

By midsummer, though, Obama had problems as President that overshadowed, at least publicly, the progress being made in Chicago. The prolonged fight over the debt ceiling, during which Obama became the face of a dysfunctional political system, had left him at his weakest point.

Crossroads GPS spent $16m on negative ads during that period, and although that was largely it for the year, the ads did damage. Obama scraped bottom in August 2011 when a Gallup poll showed his job approval rating at 38 per cent. "We had entered Jimmy Carter territory," the second senior White House official said.

Discouraged, Obama left for his summer break on Martha's Vineyard. It was a time to figure out the future. "The president was at the centre of the thought process after the debt ceiling," the second senior adviser said. "He knew where we were, and he was very frustrated with where we were."

During the next months, Obama injected a new populism into his message, culminating with a speech in Osawatomie, Kansas. "This is a make-or-break moment for the middle class and all those who are fighting to get into the middle class," Obama said. "At stake is whether this will be a country where working people can earn enough to raise a family, build a modest savings, own a home and secure their retirement."

It was the essential message, delivered variously as an attack against Romney and as a pledge to voters, of his campaign to come.

When Romney launched his campaign in June 2011, he offered himself as the lone Republican who could nurse the ailing economy back to health. He was back for a second try at the White House, and this time his advisers believed their man, a turnaround specialist during years in the private sector, had met his moment.

What was unclear then was the toll the Republican primaries would take over the next 10 months. When Rick Santorum finally suspended his campaign in April of this year and Romney emerged as the presumptive nominee, he was battered and broke. He had spent most of the roughly $100m he had raised and would not be able to tap into his general election funds until after the August convention.

His political image was in tatters, too. He had turned to the right to secure the nomination, complicating his general election run. He suggested "self-deportation" to remove immigrants in the country illegally, and on Tuesday, Latinos turned out overwhelmingly in favour of the president. "We wanted the primary to end earlier than it did," said Beth Myers, a senior adviser and Romney confidante. "We recognised we were at a tactical disadvantage for this period. Everything we did had to really matter."

By then, the Obama campaign strategy to go after Romney's business career had been set. But the Romney campaign thought it was prepared. Throughout 2011, Romney aides researched each of the roughly 100 deals that Bain Capital made during the his tenure as chief executive so they could prepare for criticism. When it came in the GOP primaries, Romney easily turned it away, accusing his opponents of attacking success itself.

That instilled a false sense of confidence. When Obama began going after Romney's time at Bain, advisers in Boston convinced themselves it already had been litigated. "The Bain attacks were arrows that just bounced off Mitt Romney," Fehrnstrom said. "They didn't do lasting damage."

The Obama campaign thought otherwise. Deputy campaign manager Stephanie Cutter argued for a series of Bain-related ads in the late spring. A Massachusetts native, Cutter had studied Romney's unsuccessful 1994 bid to unseat then-senator Edward Kennedy and the role Bain had played in it. There was a playbook, and Cutter, as much as anyone, knew it.

In May, the ads began. "Bain Capital walked away with a lot of money that they made off this plant," a former employee at GST Steel, a company bought by Bain and eventually closed down, said to the camera. "We view Mitt Romney as a job destroyer."

It also looked, at first, like a mistake. Democrats including former president Bill Clinton condemned the ads as unfair to capitalism. But at Romney headquarters, senior officials noticed alarming movement in their internal polls.

"It was the cumulative weight of everything they were doing that moved numbers, changed impressions and made it more difficult for us to climb out of the political hole they put us in," said Neil Newhouse, Romney's pollster. "We knew it was hurting. But it was a matter of how long can we survive and how can we raise money to push back."

Complicating the campaign's response was Romney's discomfort discussing his personal wealth. With an estimated net worth of between $190m and $250m, Romney is one of the richest Americans ever to win a major party's presidential nomination, and he has never been at ease talking about it.

Romney refused to disclose more than two years' worth of tax returns and finally did so only under pressure, leading Democrats to suggest that he was hiding something. That image was reinforced by Romney's planned expansion of his California beach house and the couple's summer getaways to their lakeside compound in New Hampshire.

The Romney campaign fought back, complaining about articles they believed contained factual inaccuracies. But advisers chose not to air a number of positive testimonials from business leaders that they lined up on Romney's behalf. The campaign lacked money, and did not want to distract from the candidate's core case against Obama's economic record.

The Republican super political action committees (PACs), sitting on millions of dollars, also decided not to defend Romney at a time when the campaign could not afford to defend itself. This became a source of deep frustration for some campaign strategists who were legally barred from co-ordinating with outside groups. One adviser lamented, "We didn't have any of our allies providing us any kind of cover."

The Republican problem may also have been the message – or the lack of a single one. During one week over the summer, the three big GOP super PACs had a different anti-Obama ad up featuring a distinct aspect of his record, including the government's role in the failed solar-panel manufacturer Solyndra, the lack of jobs, and the rising federal debt. The Romney campaign was hitting Obama for allegedly diluting welfare reform.

All touched on the Republicans' central theme – that Obama had failed in his management of the economy – but the impression left on voters may not have been as indelible as the Democratic effort. Even before Romney secured the nomination, his advisers began discussing potential running mates, and the habitually cautious candidate made clear that he did not want to repeat the error of 2008, when John McCain made a dramatic pick in Sarah Palin but failed to run a thorough vetting.

The selection of Paul Ryan, a conservative favourite from Wisconsin, would pose other challenges later. But when Ryan, 42, stepped off the USS Wisconsin as Romney's running mate on 11 August, it delighted the Republican base.

Within the Obama campaign, advisers believed the Ryan pick was a mistake. Ryan was not well known enough in his home state to help Romney win it, and his conservative positions on fiscal and social issue were likely to bother some independents. "They were coming up to a convention that was essentially a hostile gathering for Romney," the third senior Obama campaign official said. "He thought Ryan would help with that."

Even inside Romney's campaign, some advisers worried Ryan would be identified too closely with his proposal to turn Medicare into a voucher programme, an idea that could alienate seniors critical in Florida. Those concerns translated into disagreements between Ryan and the leadership in Boston. One week after his selection, Ryan gave a speech about Medicare to residents of the Villages, a city-size retirement community in central Florida. "We want this debate. We need this debate. We will win this debate," he declared.

To the relief of Romney's advisers, the debate never materialised. But they did not allow Ryan to set the agenda again.

As part of his role, Ryan had wanted to talk about poverty, travelling to inner cities and giving speeches that laid out the Republican vision for individual empowerment. But Romney advisers refused his request to do so, until mid-October. As one adviser put it, "The issues that we really test well on and win on are not the war on poverty."

After a troubled summer trip to Britain, Poland, and Israel, Romney placed foreign policy to the side. The overseas excursion, described by a member of Romney's national finance committee as "a mistake from beginning to end," had been followed by an awkward convention. The Romney campaign searched for something to turn its fortunes around.

On 11 September, amid developing reports about an attack on US diplomatic missions in Egypt and Libya, Romney aides found a political opportunity. Hours earlier, the US Embassy in Cairo had issued a statement responding to outrage in Egypt over an anti-Muslim film made in California. Romney's advisers viewed the statement as misplaced sympathy for the attackers. Within hours and with the blessing of his foreign policy advisers, Romney approved a statement that accused Obama of sympathising with anti-American interests in the Muslim world. It was sent out shortly after 10pm.

By early the next day, it was clear to Romney that they had acted too quickly. The campaign learnt that four Americans had been killed in an attack on a US mission in Benghazi, Libya, including the ambassador, Christopher Stevens. Even to some Republicans, Romney's hasty statement looked insensitive. "We screwed up, guys," Romney told aides that morning. "This is not good."

His advisers told him that, if he took back his statement, the neoconservative wing of the party would "take his head off." He stood by it during an appearance in Florida. Two days later, Obama travelled to Joint Base Andrews to meet the four flag-draped coffins. From then on, including during the final debate on foreign policy, Romney was reluctant to engage Obama on the Libya attack, a useful way to discredit his otherwise strong record on national security issues. "The governor felt snake bit by the reaction to our public pronouncement," said one senior adviser. "I think it made him shy about aggressively prosecuting the Benghazi case against the Obama administration."

The Obama campaign moved quietly through Romney's bumpy summer, and then, for a candidate who has enjoyed moments of good fortune through his political career, another one came. On 17 September, less than a week after the Benghazi attack, Mother Jones magazine began publishing secretly recorded footage of Romney speaking derisively about "the 47 per cent" of Americans who pay no income taxes at a spring fundraiser. "I'll never convince them they should take personal responsibility and care for their lives," he told the guests, who paid $50,000 to attend. The video played perfectly into the image, showcased in Obama's Bain ads, of Romney as a candidate whose chief concern was protecting the wealthy. "It reinforced a negative perception of the governor that was being peddled by our opponents, so yeah, of course we were concerned about it," Fehrnstrom said.

Those close to Ryan, whose idea of talking about rising poverty was rejected by the campaign, were also frustrated. "If we had been speaking out about these issues before this happened, it would've inoculated us a little bit," an adviser said. Within a few hours of the video's release, Romney conceded that his remarks were "not elegantly stated." The campaign hit a low point.

In Chicago, Cutter, the deputy Obama campaign manager, and Ben LaBolt, the communications director, walked into Axelrod's office within minutes of the video posting on the magazine's website to decide what to do.

By the end of the day, the campaign had issued a statement denouncing Romney for "writing off half the nation". Then, for a few days, it stood back and watched.

Within 36 hours, Priorities USA aired an ad about the taped comments. And the Obama campaign followed with its own, using Romney's words behind a series of black-and-white photos of working Americans, veterans and seniors.

In the week that followed, Obama widened his lead in the polls. The race appeared over as October approached, the incumbent cruising to a win. But inside the Obama campaign the new polling showed something that senior advisers worried would not last. The post-47 per cent surveys reflected a migration of Republican-leaning independents toward Obama. Whether they would be there on election day was uncertain, and that question occupied Obama advisers as the president left for a resort outside Las Vegas to prepare for the first debate.

For weeks, Obama had resisted the intensive practice that his advisers wanted him to take on. He was the President now, and even those closest to him had a harder time ordering him to do something he didn't want to do. And he didn't want to prepare for the debate, one of those political duties, such as donor phone calls, that Obama disdained. "It's a drag," Obama told the staff. "They are making me do my homework."

Trailing in the polls, Romney knew the debate was perhaps his last opportunity to reverse the trajectory of the race. During flights between campaign stops or in his hotel room before bed, he studied. The preparation paid off. In the hours after Romney's successful debate, his advisers began seeing encouraging data. His "47 per cent" remarks had nearly disappeared from the concerns that voters expressed to the campaign's pollsters.

Romney had pushed around Obama, who appeared alternately sleepy, distracted and peevish. And the conservative Republican from the primaries had made a swift turn to the centre on a number of issues important to independent voters. Calls from nervous donors flowed into the Obama campaign, and within days, a series of polls suggested the race was again too close to call a month before election day. To Obama's advisers, the gains from Romney's stumbling September vanished in a night.

"The rubber band that had stretched toward us the previous month suddenly snapped back to where it was," said the second senior Obama campaign official. Obama was angry with himself and began studying the tape in preparation for the second debate that was more than a week away.

The polls showed Romney gaining steadily, despite a good September jobs report released days after the debate that showed that the unemployment had fallen to the lowest point since the month that Obama took office. As nervous Democrats wondered whether Obama had given the election away, the Vice- President, Joe Biden, was asked to steady the base in his debate against Ryan. Unlike Obama, Biden had been preparing, off and on, for months. Advisers had put together 100 questions that Biden should expect to get, and during even the smallest windows of free time on Air Force Two, they would quiz the Vice-President: "So why is the economy better off than it was four years ago?"

Biden turned in an aggressive defence of the administration's record. Before he had even left the stage at Centre College in Danville, Kentucky, he was handed a mobile phone. It was Obama calling with congratulations.

The Obama campaign headquarters in Chicago thinned out in late October as some of the 700-plus staff flowed into the field. In the final days, Obama swept through swing states in an effort to rally his supporters and urge them to the polls, at one point suggesting that casting a ballot would be suitable "revenge" for a nasty campaign. He drew on "Obamadata," as the campaign refers to its voter lists, to hold conference calls directly with thousands of voters and volunteers. Romney, too, bounced through Ohio, Virginia, Florida. Polls showed narrow leads — for both candidates — with little over a week to go before Election Day.

Then Hurricane Sandy arrived, stalling out the campaigns. It couldn't have come at a worse time for Romney. Obama left the trail for the White House, taking charge of an emergency response that even some Republicans praised.

The New Jersey Governor, Chris Christie, was among them. For months, Christie had been one of Romney's staunchest allies. He had predicted Romney's knockout performance in the first debate and spoke for him whenever asked.

With days to go, Christie called Obama "outstanding" in the aftermath of Sandy and, as the two walked the storm-thrashed streets of Atlantic City, he noted that he could not "thank the President enough for his personal concern and compassion for our state."

Six days later Obama secured his second term.

Washington Post