Kerry boosts poll standing after head-to-head debate with Bush
But analysts doubted whether the Democrat had done enough to snatch the lead back from his rival.
Watched by an audience of more than 50 million Americans, the candidates clashed in Florida on how they would prevail in Iraq and win the war on terror.
A poll by ABC News after the debate found 45% of voters handed victory to Kerry and 36% to Bush but a small majority continued to back Mr Bush for re-election.
In a CBS poll of uncommitted voters, Mr Kerry came out on top with 43% against 28% who chose the president.
The general consensus among neutral political pundits was that Mr Kerry gave the best performance.
Neither man managed to deliver a knock-out punch during the 90-minute debate at Miami University.
Mr Kerry accused his rival of a "colossal error in judgement" by invading Iraq and offered a "fresh start" for America.
But Mr Bush hit back, saying he had proved himself as a leader and that the world was safer with Saddam Hussein removed.
Mr Kerry accused Mr Bush of misleading America into the Iraq war. "Iraq was not even close to the war on terror until the president invaded it," the Massachusetts senator said.
"He rushed to war in Iraq without a plan to win the peace," he said, adding: "We did not go as a last resort."
"That's not a judgement the President of the United States ought to take."
Mr Kerry said US forces should have instead focused on capturing Osama bin Laden after the September 11 terror attacks.
He said: "We need to be smarter about how we wage the war on terror."
But Mr Bush repeatedly said his opponent was sending "mixed messages" on the issue of Iraq.
Mr Bush also accused Mr Kerry of "denigrating" allies, including Britain and Poland, with his insistence that the US was practically alone in Iraq.
Mr Kerry pointed out Iraq was not behind the September 11 attacks. He reinforced a central theme of his campaign, vowing to win back America's allies.
"We need a fresh start, a new credibility and a president who can bring new allies to our side," he said.
But Mr Bush argued world politics was not a popularity contest.
"Trying to be popular in the global sense, if it's not in our interests, makes no sense," he said.
Both men agreed that the biggest threat facing the US was nuclear proliferation.
During the debate, Mr Bush appeared perturbed when his opponent levelled charges, scowling and looking away in apparent disgust at times.
Mr Kerry stood with an impassive stare when Mr Bush spoke. The two men will go head-to-head again on October 9 in St Louis, Missouri and on October 14 in Tempe, Arizona.




