MIAMI (AFP) - The two men vying for the presidency of the United States hunkered down like school boys to cram for a televised debate that might be Democrat John Kerry's last best hope of overtaking President George W. Bush.
Tens of millions of viewers were expected to watch Thursday's 90-minute face-off at the University of Miami, with the president holding a clear lead less than five weeks before the November 2 election.
Kerry, cloistered at a hillside resort in the Midwestern state of Wisconsin to prepare for the first of three debates, acknowledged the Republicans had drawn blood with attacks on him as weak and waffling on national security.
"I think their advertising and their effort over these last months, to use that word, have been particularly successful. I give them credit for it. But it doesn't reflect the truth," the Massachusetts senator told ABC television.
He said the Republicans had scored points by taking his remarks out of context and noted that the debate would be "an opportunity to be able to really let the American people know the truth and know where you stand."
Bush, leading in most national polls by five to eight points, was holed up on his Texas ranch, studying for the debate that will focus on his strong points of foreign policy and national security.
But he did take time to discuss family questions with a popular TV psychologist on a program to be broadcast Wednesday and widely watched by women, a coveted voting bloc in this year's election.
His campaign manager, Ken Mehlman, provided an early taste of the president's line of attack Thursday in an e-mail to supporters that ridiculed Kerry's various statements on the war in Iraq.
"He is currently against the war and wouldn't have gone to war, but he used to be for the war before he was against the war he voted for before he was against it," Mehlman wrote.
The debate will be the first head-to-head meeting of Bush and Kerry in the race, which has become increasingly nasty, with each candidate flailing away at the other's credibility and leadership capacity.
Most analysts agreed the burden was on Kerry to reverse nagging impressions on the part of many voters that he had flip-flopped on Iraq and other issues and failed to offer clear policy alternatives to the Bush administration.
Although three debates are scheduled, the first usually has the largest impact. The stakes are particularly high Thursday for Kerry, since he has made Iraq a focus of his campaign, said David Moore, a senior editor with the Gallup polling group.
"If he doesn't make good in this debate, ... then he certainly lost a major opportunity and it's going to be doubly difficult for him to try to catch up in the subsequent debates," Moore told AFP.
A quarter of voters or more believe this year's debates could affect their choice, according to opinion polls. In one survey by Time magazine, seven in 10 "swing" voters said the sessions could be determining factors.
But in the 44-year-old tradition of televised US presidential debates, there are few examples in which a candidate trailing by a significant margin has been able to reverse the momentum with a single strong showing.
The sessions did have a decisive impact in the 1960 race between Richard Nixon and John F. Kennedy and the 1980 clash between Jimmy Carter and Ronald Reagan, but both were extremely close going into the debate.
Presidential historian Eric Davis, a professor of political science at Middlebury College in Vermont, said Kerry's chances of turning the campaign around in one night Thursday were "not very great."
"I think Kerry needs to be thinking about this in terms of three debates, not just one. Tomorrow night, sort of stop the hemorrhaging, stop the loss of support for Bush and then hope to reverse things in the two to come."
Kerry and Bush will appear at a "town hall" debate on October 8 in the Midwestern city of St. Louis, Missouri, and finish with a session on domestic policy October 13 in the western city of Tempe, Arizona.
Vice President Dick Cheney and Kerry's Democratic running mate, John Edwards, will hold a single debate on all questions October 5 in the Midwestern city of Cleveland, Ohio.