WASHINGTON // The debate may not prove decisive in a campaign in which momentum has lurched from one candidate to the other.
But Barack Obama, the US president, should at least believe he did well enough in the second presidential bout in New York on Tuesday night to put his performance in the first behind him.
Yet to be seen, however, is whether the more assertive Mr Obama, who pounced on Mitt Romney, his Republican rival, from the start of the debate, will see a similar bump in the polls that helped Mr Romney turn around a previously moribund race after the first debate on October 3.
Certainly his performance will fire up the Democratic base, said Lorenzo Morris, a professor of political science at Howard University in Washington DC.
The president's supporters had reacted negatively to his "unusually reserved" performance in that first debate, Mr Morris said.
"Obama appealed to the diverse Democratic constituency last night by being aggressive because at least he pointed out that he was willing to fight his opponent's conservative agenda."
But that may not be enough to turn momentum that, during the past few weeks, had swung in Mr Romney's favour, said Christian Whiton, a political consultant with DC International Advisory and a former foreign policy adviser to another former Republican presidential hopeful, Newt Gingrich.
"If voters simply need to see in these debates that Romney is credible in order to dump an incumbent who hasn't delivered, then Romney's recent turnaround should continue," Mr Whiton said.
Credibility is very much an issue in an election campaign in which both the incumbent president and his Republican challenger have been vague over how exactly they would tackle a host of issues, including what is seen as the top concern for US voters: America's unemployment problem and the country's huge budget deficit.
Mr Obama said he would continue to invest in infrastructure and education even as he eases the tax burden on middle-class families - balancing it out by raising taxes on the wealthy.
In the first debate, Mr Romney had ridiculed that approach as "trickle-down government". On Tuesday, he insisted that his own five-point plan for tax cuts accompanied by closing tax loopholes, could "get America working again" and help balance the budget.
This time, Mr Obama had a ready answer: "Governor Romney doesn't have a five-point plan. He has a one-point plan. And that plan is to make sure that folks at the top play by a different set of rules."
Mr Romney put a dent in his own credibility by misstating what Mr Obama said on the day after the September 11 attack on the US consulate in Benghazi that left four Americans dead.
US intelligence has now deemed it a terrorist attack, a conclusion the administration was slow to reach. Nevertheless, Mr Obama did refer to it as a terrorist attack at the White House on September 12.
Mr Romney found himself corrected on the spot by the moderator on the only foreign policy issue raised in the debate.
Both candidates tried to reach out to potentially crucial voting blocs. Mr Obama has a strong advantage among Hispanic voters but Mr Romney repeated that he would not grant "amnesty" to those in the US illegally, though he was vague about how he would deal with the children of illegal immigrants.
Mr Romney also didn't fare well on the question of women, although women voters had increasinglybeen turning to Mr Romney before the debate.
A Gallup/USA Today poll before Tuesday's debate showed him pulling ahead of Mr Obama by 4 per cent among likely voters in the crucial 12 battleground states, largely due to greater support from women.
But Mr Romney inadvertently managed to spark an internet sensation when he said he had received "binders full of women" to consider for jobs when he served as governor of Massachusetts.
He may also have raised an eyebrow by suggesting that, in the economy he envisioned, employers were "going to be so anxious to get good workers they're going to be anxious to hire women".
Mr Whiton suggested that Mr Romney successfully "posed a key point of his candidacy: 'If you re-elect Obama, you know what you're going to get' regarding economic performance.'"
But Mr Obama's strategy was to show that the opposite was also true. A vote for Mr Romney is a vote for the unknown, he said, referring to Mr Romney's comments disparaging 47 per cent of the country as "victims who refuse personal responsibility", according to a secret recording of a closed May fund-raising event.
"Obama came to play on Tuesday," said Steve McMahon, a Washington DC based consultant. "Romney upset the structure of the campaign for a while. Obama has put it back on track."