DENVER - President Barack Obama and Republican Mitt Romney come face to face for the first time in the presidential campaign Wednesday night for a high-risk nationally televised debate that offers the challenger his best opportunity to revive his struggling presidential campaign.
Romney, running short on time to reverse his fortunes, is angling for a breakout performance in the three 90-minute presidential debates scheduled over the next three weeks.
Obama, well aware that the remaining five weeks of the race still offer enough time for Romney to catch up, is determined to avoid any campaign-altering mistakes as he presses his case for a second term.
The candidates will be speaking to a TV audience of tens of millions in one of those rare moments when a critical mass of Americans collectively fix their attention on one event. Fifty-two million people tuned in to the first debate four years ago, and 80 per cent of the nation's adults reported watching at least a bit of the debates between Obama and Republican John McCain.
Though polls show the race remains tight ahead of the Nov. 6 vote, Obama clearly has momentum and the edge not only in national polls, but in the battleground states that will effectively decide the election.
Romney's campaign is looking to regain ground on Obama after falling further behind in the wake of a secretly recorded video showing the Republican telling campaign donors that 47 per cent of Americans pay no federal income tax and believe they are victims who are entitled to government assistance. As a candidate, he said, "my job is not to worry" about them.
Recent polls show Obama with a modest lead in many of the nine battleground states that will decide the election, and all but two of those states have early voting, meaning more people are already locking in their votes every day. The most important of those states, Ohio, started early voting Tuesday.
But Republicans with access to Romney's polling data said Tuesday that he has begun regaining some support among independent voters, enabling him to cut into the president's advantage.
Because the presidential election is not decided by popular vote but rather by in a state-by-state contest, a handful of so-called battleground states, which do not reliably vote either Republican or Democratic, will likely decide the race.
Wednesday's 9 p.m. EDT (0100 GMT) faceoff between Obama and Romney on domestic policy, moderated by Public Broadcasting Service newsman Jim Lehrer at the University of Denver, is sure to offer a blend of choreography and spontaneity: Both men have spent hours rehearsing with proxy opponents — yet know to expect the unexpected.
"That's what so tricky about this," says Alan Schroeder, author of a book on presidential debates. "There's never a template for preparing because each one takes its own direction."
Half of the six, 15-minute debate segments have been allotted to topics related to the economy. The last three segments will focus on health care, the role of government and governing.
Romney has pinned his campaign on the argument that Obama has failed to adequately juice up the U.S. economy. But this effort has been complicated by recent polls showing growing public optimism about the economy and the president's leadership.
In recent days, Romney has emphasized criticism of the president's foreign policy, particularly in the Middle East, where a terrorist attack at the U.S. Consulate in Benghazi, Libya, left Ambassador Christopher Stevens and three other Americans dead.
Republicans tried to frame the economic debate in their terms Tuesday by pointing to Vice-President Joe Biden's passing reference to "a middle class that has been buried the last four years" at a campaign stop Tuesday in North Carolina. They cast the vice-president's comments as an unwitting acknowledgement that Obama's economic policies have devastated average Americans.
"We agree," Republican vice-presidential nominee Paul Ryan declared in Iowa. "That means we need to stop digging by electing Mitt Romney the next president of the United States."
Obama's camp countered that it was the policies of the president's Republican predecessors that had caused the damage.
Biden, at a later campaign event, was careful to say that "the middle class was buried by the policies that Romney and Ryan supported," calling their economic plans an amped-up rework of those from the George W. Bush years.
In a quadrennial pre-debate ritual, each campaign has worked overtime to raise expectations for the opponent while lowering the bar for its own candidate. The thinking is that it's better to exceed lukewarm expectations than to fail to perform at an anticipated level of great skill.
But both men are seasoned debaters: Obama has been here before, facing off with McCain in 2008. Romney hasn't gone one-on-one in a presidential debate, but he got plenty of practice thinking on his feet during the 19 multi-candidate debates during the Republican primaries.
On a long day of debate prep — Romney in Denver and Obama in Henderson, Nevada, near Las Vegas — both candidates tried to blow off some steam Tuesday. The president made a tourist's visit to nearby Hoover Dam, reinforcing his emphasis on government's vital role in building key infrastructure, and Romney fit in a lunchtime outing to a Mexican grill for a burrito bowl.
Obama and Romney have a two-track mission with debate viewers: Motivate core supporters to turn out and vote — at a time when early voting already is under way in many states — and try to lock in some new supporters from among the small subset of viewers who haven't settled on a candidate or whose support for one man or the other is squishy.
The viewers who matter most live in the contested battleground states that will determine which candidate emerges victorious on Nov. 6: Colorado, Florida, Iowa, Nevada, New Hampshire, North Carolina, Ohio, Virginia and, to a lesser extent, Wisconsin.
Romney and Obama debate again Oct. 16 in Hempstead, New York, and Oct. 22 in Boca Raton, Florida. Biden and Ryan have their lone debate on Oct. 11 in Danville, Kentucky.
Obama plans to use the first presidential debate as the hook for fundraisers and recruiting volunteers. Former President Bill Clinton will be in Boston on Wednesday night for Obama, with donors paying $20,000 a person. .
The Obama campaign plans more than 4,000 debate-watching events around the country. And Biden is scheduled to hold a live discussion with supporters streamed online after the debate.
The Romney camp planned 336 debate parties at restaurants, bars, grills, Veterans of Foreign War halls and other sites concentrated in battleground states.
Associated Press writers Kasie Hunt, Ben Feller, Steve Peoples and AP News Survey Specialist Dennis Junius contributed to this report.