Obama seizes the moment by detailing his strategy for restoring confidence in markets

As the early voting in the US presidential election was getting under way, Barack Obama last night attempted to seize all possible advantage from the crisis on Wall Street announcing the approach he would take to restore confidence in staggering financial markets.

Mr Obama, who is being criticised for saturating the airwaves with negative advertising, outlined principles for addressing the crisis after huddling in Miami with a clutch of prominent economists, many of them former Bill Clinton aides, including Lawrence Summers and the former Treasury secretary Robert Rubin.

With the Bush administration unveiling its own blueprint for action to end the financial turmoil, the Obama presentation was no more than campaign posturing. It came, however, as both candidates sought to show that they would be best able to deal with a crisis of such great scope.

The emergency may become the "September Surprise" that completely changed the course of the 2008 race. Supporters of Mr Obama hope it will spur Americans to blame incumbent Republicans for the mess and turn their backs on John McCain. It is equally possible, however, that this moment of deep uncertainty may discourage them from voting for Mr Obama, whom they may regard as too inexperienced.

It is a pivotal moment that comes just as some Americans get their first chance to exercise their judgement. The first ballots were being cast yesterday as early voting stations opened in Virginia. To encourage higher turnout, early voting will be allowed in 36 states this year, meaning that one third of all voters could make their choice before 4 November, the official election day. A sombre Mr Obama appeared before the cameras flanked by Mr Rubin and Laura Tyson, the former dean of the London Business School. "This is not a time for fear, it is not a time for panic. It's a time for resolve and it's a time for leadership. Our nation has faced even more difficult times."

Mr Obama held back from offering a plan that would directly compete with the one presented in Washington last night by the Teasury Secretary, Henry Paulson, saying it was not a time for partisan warfare. He said the response to the crisis should respect four principles: any steps should help Main Street – ordinary Americans – as much as Wall Street, should not be seen to reward irresponsible actions by financial firms, should be temporary in nature and should be co-ordinated globally with the Group of Twenty.

It was not by accident that Mr Obama chose Florida to make his economic pitch. While early voting in that state does not begin for a month, the first absentee ballots were being posted yesterday. Recent polls, meanwhile, have portrayed Florida as a toss-up, perhaps tending slightly towards Mr McCain.

Mr Obama will address another rally in Florida today. "The days are ticking down, and I believe this campaign visit is very, very important," said Terrie Brady, a former state Democratic Party chairman. "If he stays on message, it will be a home run. Like Bill Clinton said, 'It's the economy, stupid'."