By John Whitesides, Reuters Political Correspondent
After months of long-distance political brawling, the two US major-party presidential candidates, Republican John McCain and Democrat Barack Obama, meet face-to-face on Friday in the first of three debates that could prove crucial in a tight race for the White House.
The 90-minute encounters are expected to draw huge television audiences and give undecided voters their first chance to directly compare the two presidential contenders before the 4 November election.
The historic nature of the campaign - Senator Obama is the first black presidential nominee of a major party - and the urgency of war in Iraq and a meltdown on Wall Street lends further drama to a series of debates that will overshadow all other campaign activity in the next three weeks.
The audience for the debates is expected to dwarf the approximately 40m television viewers who watched each candidate give an acceptance speech at their nominating conventions.
'This could be the crucial moment in this campaign. You get relatively few chances to make a lasting impression,' said Steven Schier, a political scientist at Carleton College in Minnesota.
Opinion polls show many voters remain undecided or persuadable as the White House race nears its final stretch. Mr Obama, 47, a first-term Illinois senator who is relatively new to the national scene, has had a particularly difficult time easing voter concerns.
'Obama seems unable to close the deal with voters, and this is his best and probably last chance to allay whatever doubts remain about him,' said Alan Schroeder of Northeastern University in Boston, who has written a history of presidential debates.
'A lot of people who are undecided wait for the debates to begin making decisions. It is when things get serious for the general public and candidates reach that last sliver of the audience that has not been paying attention,' he said.
Friday's first debate at the University of Mississippi in Oxford will focus on foreign policy and national security, an area of strength for Senator McCain, 72, a former prisoner of war in Vietnam who has been a staunch advocate of U.S. military involvement in Iraq.
Mr Obama's aides have tried to ramp up expectations for Mr McCain, noting the topic plays to the strengths of the four-term senator from Arizona and 26-year veteran of Washington.
'It's a challenging debate for us. Senator McCain has repeatedly made the point about his extensive foreign policy experience,' said David Axelrod, Sen Obama's chief strategist.
The debates begin as Congress and the administration of President George W Bush hammer out the details of a historic $700bn (€475bn) bailout of financial markets that has dominated the campaign.
Economic Crisis Could Play Crucial Role
Mr Axelrod said the global nature of the crisis would make it likely to be a topic in the first debate despite the focus on foreign policy.
'We'll be prepared to talk about it,' he said.
Senator Obama heads to Tampa, Florida, on Tuesday for three days of debate preparation, and Senator McCain is expected to spend some time in debate preparation this week before heading to Mississippi.
The vice presidential candidates, Democratic Senator Joe Biden of Delaware and Republican Governor Sarah Palin of Alaska, will debate on 2 October. The second presidential debate is 7 October and the last one is 15 October when the economy will be the topic.
Presidential debates have rarely been decisive, but they can switch momentum or change perceptions. Democrat Al Gore was leading Republican Bush in the polls in 2000 until his loud sighs and supposed misstatements in the first debate became an issue.
Many analysts have likened Mr Obama's debate task to the 1980 race when Republican Ronald Reagan challenged President Jimmy Carter. After a strong performance in the sole debate eased doubts about him, Mr Reagan pulled away to win.
'People already think of Obama as a great orator. Now he's got to prove himself presidential,' said David Steinberg, a political communications expert and debate coach at the University of Miami in Florida.
Both campaigns will be ready to pounce on misstatements or gaffes, particularly if they match the existing narrative about their opponent heading into the debate.
For Senator Obama, that means any statement that feeds the perception he is inexperienced could become a flash point. For Senator McCain, a false statement will reinforce the perception he has not been truthful in the campaign and bouts of forgetfulness could remind voters of his age.
In the era of 24-hour cable news networks, radio talk shows, late-night comics and Internet political chatter, the story line that emerges from the debate can become more important than any pronouncement in it.
Little things become big stories, like Mr Gore's sighs or the glance at his watch by President George H W Bush, the current president's father, during a 1992 debate with Bill Clinton and Ross Perot.
'Those little moments can substitute for the debate and overtake it, and take on a life of their own,' Mr Schroeder said
