Almost two weeks ago, Republican President George Bush headed into his first debate with Democrat Senator John Kerry, with a solid lead in national polls. But the presidential race has narrowed since then, following two presidential debates watched by tens of millions of viewers.

More than 60 million people watched the first face-off between President Bush and John Kerry in Miami. A small number of them questioned by poll takers said Mr. Kerry was the winner. The Democratic party Senator raised doubts about President Bush's judgment in taking the United States to war in Iraq. Many analysts suggested Mr. Bush appeared defensive and annoyed. "He just said, the enemy attacked us. Saddam Hussein didn't attack us. Osama bin Laden attacked us. Al Qaida attacked us," Senator Kerry said at one point. President Bush replied, "First listen, of course I know Osama bin Laden attacked us. I know that."

Public opinion polls showed many viewers felt the president repeated himself too much when talking about the war in Iraq. "It's hard work. Everyone knows it's hard work," he said.

But analysts and viewers agreed Mr. Bush regained momentum in the second debate in St. Louis, a "town hall" forum that allowed both candidates to take questions from an audience of undecided voters.

Again and again, Mr. Bush accused Mr. Kerry of constantly changing his mind and being weak on terrorism. "I don't see how you can lead this country in a time of war, in a time of uncertainty if you change your mind because of politics," Mr. Bush said.

Mr. Kerry consistently hit back, charging Mr. Bush's campaign with unfairly attacking his character and trying to scare voters. He cited a new report by the chief U.S. weapons inspector, which concluded that Iraq possessed no weapons of mass destruction when the war began. "The president didn't find weapons of mass destruction in Iraq so he's really turned his campaign into a weapon of mass deception," Mr. Kerry said.

On domestic issues, Mr. Bush repeatedly portrayed Mr. Kerry as a liberal who would raise taxes on the middle class to pay for big government programs. "You can run but you can't hide. He voted 98 times to raise taxes, these aren't made-up figures," the president said.

Mr. Kerry blamed the president for a soaring deficit and tax cuts for the rich. When asked by a voter to promise not to raise taxes on families making less than $200,000 a year, Mr. Kerry replied. "Yes, right into the camera, yes. I am not going to raise taxes. I have a tax cut," he said.

On the eve of the debate in Tempe, Arizona, Mr. Bush leads in some polls, Mr. Kerry in others. With the race a virtual dead heat, this final debate could be decisive.