From early pace-setter to surprise drop-out: Where did it all go wrong for Kamala Harris?

She was a former state prosecutor and a US senator whose encouraging poll numbers and early popularity raised the potential prospect of voters electing the country's first African-American woman as president.

But by the time she dropped out of the race for the Democratic nomination, Kamala Harris had run out of money and had faced a virtual mutiny among her campaign staff as internal division and strategy failures reached a boiling point.

Ms Harris, who endured 11 months on the campaign trail, including several nationally televised debates, announced to her supporters and staff with "deep regret" and "deep gratitude" that she "simply doesn't have the financial resources we need to continue."

"I'm not a billionaire", she said. "I can't fund my own campaign. And as the campaign has gone on, it's become harder and harder to raise the money we need to compete."

The announcement follows reports that billionaire Michael Bloomberg spent nearly $60m on advertising in recent weeks, and that Tom Steyer, another billionaire who has spent more than $60m on ads since July. Both men are white.

Her departure leaves one less person of colour in the remaining field of 15 Democratic contenders, of which 10 are white; all six candidates who qualified for December debates so far are white.

Before she announced the end of her campaign, Ms Harris was the only non-white candidate to qualify for that debate.

Her departure from the race also has underscored allegations of racism and sexism directed at the media status quo as her campaign struggled to gain a foothold among other Democratic contenders.

Ms Harris said her campaign "uniquely spoke to the experiences of Black women and people of colour — and their importance to the success and future of this party. Our campaign demanded no one should be taken for granted by any political party."

"We will keep up that fight because no one should be made to fight alone", she said. "And I believe our campaign showed every child in America — regardless of their colour or gender — that there are no limits to who can lead and hold positions of power in our country."

Ms Harris's political rise began as a San Francisco attorney general, followed by her election to California state attorney general and the US senate. She became only the second black woman to enter the US Senate when she took office in 2017.

But as soon as she entered the race, Ms Harris endured criticism for inconsistent messaging on health care and criminal justice, vacillating between a progressive-minded reformist and a safer, more moderate candidate that could compete alongside more conservative Democrats like Joe Biden.

She told donors she was "not comfortable" with a Medicare-for-All plan and removed her support for a bill sponsored by Vermont Senator Bernie Sanders, among her campaign rivals.

Among her biggest political challenges was a plan to navigate a progressive criminal justice platform while answering for her record as a "smart on crime" prosecutor.

She rose to power as a top prosecutor amid a climate of progressive organisers and politicians drawing bipartisan reform aimed at addressing vast racial disparities in the criminal justice system.

But her record as a prosecutor included harsh penalties for marijuana offences and threats to prosecute children as part of an anti-truancy push. She also has maintained her personal opposition to the death penalty, but as California's top prosecutor she said she would fight to maintain it.

Shortly after announcing her candidacy, she said: "The bottom line is the buck stops with me, and I take full responsibility for what my office did."

A New York Times op-ed, titled "Kamala Harris Was Not a Progressive Prosecutor," said if the senator "wants people who care about dismantling mass incarceration and correcting miscarriages of justice to vote for her, she needs to radically break with her past."

Ms Harris revealed a platform that aimed to eliminate the death penalty, cash bail and private prisons, building on transformative policies she has supported as a senator.

She delivered arguably the most memorable blow on the debate stage, where she stunned Mr Biden for his defence of segregationist politicians and opposition to desegregation efforts in public schools. During a June debate, Ms Harris said: "There was a little girl in California who was part of the second class to integrate her public schools, and she was bused to school every day, and that little girl was me."

Mr Biden cut his response short before his time was up.

It was a critical attack on the centrist call for "civility" while underlining crucial priority differences among the candidates, shaped largely by perspectives informed by their race.

Her debate appearance attracted significant media attention and helped spike poll numbers in her favour, hitting 20 per cent at its peak.

But her rivals campaigned on more-dramatic policy proposals while she championed herself as a pragmatist, introducing policies that relied on assumptions among a voter base that remained divided.

She faced unanticipated challenges trying to build support among non-white voters by focusing on states like South Carolina and California, while rivals gained traction elsewhere.

By the third quarter of 2019, contributions to the campaign slowed while it continued to burn through its treasury.

Ms Harris had spent more than $1.41 for every dollar raised, according to reports, and was forced to lay off staff after moving offices to Baltimore, Maryland ahead of preparation for a crucial campaign in Iowa.

And within the last week, press reports charted the chaos within her campaign as it neared 2020.

A devastating November resignation letter obtained by the New York Times revealed internal division among campaign staff led by Ms Harris' sister and campaign chief Maya Harris — an adviser for Hillary Clinton on her 2016 campaign — and campaign manager Juan Rodriguez, who failed to answer questions about strategy and finances ahead of Iowa, according to the letter.

In her resignation letter, now-former state operations manager Kelly Mehlenbacher said she had "never seen a staff treated so poorly."

She said: "Because we have refused to confront our mistakes, foster an environment of critical thinking, and honest feedback, or trust the expertise of talented staff, we find ourselves making the same unforced errors over and over."

Ms Harris had abruptly cancelled a high-profile fundraiser in New York, scheduled for Tuesday, before announcing the suspension of the campaign.

Among Democrats' biggest hurdle in 2020 is demonstrating an ability to beat Donald Trump.

Out of the race, Ms Harris says she'll do continue to do everything in her power to defeat the president and "fight for the future of our country and the best of who we are."