Seated just inches apart and staring each other in the eye, Sens. Barack Obama and John McCain exchanged the sharpest barbs of the campaign, but when it was over McCain had failed to deliver a knockout blow.
The debate was possibly McCain's last chance to alter the course of a race that shows him sliding dangerously behind Obama in the polls, and McCain came out swinging, assailing Obama over his economic plan, his truthfulness and his character.
"You didn't tell the American people the truth," McCain charged at one point in the debate at Hofstra University in Hempstead, N.Y., referring to Obama's decision to forego public financing of his campaign after earlier suggesting he planned to opt into it.
Obama, however, rarely took the bait, generally appearing to remain poised and self-assured.
"He really didn't land a knockout blow on Barack Obama," ABC News' chief Washington correspondent George Stephanopoulos told "Good Morning America."
McCain started out strong in the final debate of the long presidential campaign, Stephanopoulos said but the turning point was the "tone" of the debate as McCain stayed on the offensive against Obama.
Obama also won the "battle of the split screens," Stephanopoulos said.
"Whenever he was getting attacked by John McCain, [Obama] tended to shake his head, smile, look unruffled. John McCain on the other hand when Barack Obama was talking would sometimes roll his eyes, get agitated over the course of it and a little angry," Stephanopoulos told "GMA."
The Obama camp launched a new ad just hours after the debate concluded, using footage from the showdown to highlight Obama's contention that McCain voted to back President Bush's policies more than 90 percent of the time.
The Democrat even felt compelled to warn his supporters at a New York fundraiser today to avoid getting overconfident.
"For those of you who are feeling giddy or cocky or think this is all set, I just have two words for you: New Hampshire," Obama said.
Obama was expected to win the New Hampshire primary, but lost in an upset to Sen. Hillary Clinton.
McCain will try to capitalize on the debate with an appearance tonight on "The Late Show with David Letterman".
With the last debate out of the way, the campaigns will now concentrate on winning the battleground states over the remaining 19 days, and McCain appears to be at a severe disadvantage.
"Barack Obama has a huge advantage in the final weeks. He's outspending McCain 2 to 1 on television, 3 or 4 to 1 in battleground states," Stephanopoulos told "GMA."
Obama also appears to have an edge in the polls in crucial states.
"There are seven must win states for McCain, including Ohio, Florida, Missouri, Colorado, Nevada, Virginia, and North Carolina," Stephanopoulos said. "McCain has to win every single one of those states to eek out a narrow electoral college victory, unless there's a massive shift in the race. Right now Obama is ahead or at the least tied in every single one of McCain's seven must-win states."
Though much of the debate focused on the hardships facing average Americans, embodied in a discussion of a small business owner the candidates nicknamed "Joe the plumber," the debate was marked by spirited attacks launched by both candidates.
McCain repeated the two major negative talking points of his campaign this week, calling on Obama to explain his relationships to 1960s radical Bill Ayers and the Association of Community Organizations for Reform Now (ACORN), a community group that has been accused of fraudulently registering voters.
"[Sen. Hillary] Clinton said in her [Democratic primary] debates with you [that] we need to know the full extent of your relationship [with Ayers and] with ACORN," McCain said. "All of these things need to be examined, of course."
"I'll respond to these two allegations," Obama said. "Mr. Ayers has become the centerpiece of McCain's campaign. Let's get the record straight. Ayers is a professor of education in Chicago. Forty years ago, when I was 8 years old, he engaged in despicable acts. I have roundly condemned those acts."
Obama said he served on a board with Ayers along with a former ambassador and the presidents of the University of Illinois and Northwestern University.
McCain accused Obama of lying about his willingness to take public spending and said Obama should have done more to repudiate Rep. John Lewis, D-Ga., an Obama supporter who compared campaign rallies for McCain and his running mate, Alaska Gov. Sarah Palin, to those of segregationist Alabama Gov. George Wallace.
"Congressman John Lewis said Palin and I were associated with segregation, deaths of children in church bombings," McCain said. "That to me was so hurtful. And Obama, you didn't repudiate those remarks. Whenever there have been out-of-bounds remarks from Republicans, I'd repudiate [them]."
Obama said Lewis was responding to racist and threatening language heard at McCain-Palin rallies in response to the mention of Obama's name, which the Republican candidates did little to stop.
"Lewis, he -- unprompted, without my campaign's awareness -- said he was troubled with what he was hearing at some of the rallies your running mate was holding," Obama said. "Shouting things like 'terrorist' and 'kill him' that your running mate didn't stop or mention. I think Lewis' point was that we have to be careful with how we deal with our supporters."
Trailing in the polls by as much as 14 points and facing deficits in numerous battleground states, according to a New York Times/CBS News poll, McCain is caught between giving his base what they want and going negative or responding to polls that indicate Americans are fed up with the tone of the election.
Both an ABC News/Washington Post and the New York Times/CBS News polls found that a spate of McCain attacks on Obama actually hurt McCain instead of Obama, because voters objected to his negative tactics.
Obama argued that McCain has relied more heavily on attacks than he has.
"I think we expect campaigns to be tough," Obama said. "If you look at the record ... two-thirds of the American people think McCain is running a negative campaign. One hundred percent of your ads have been negative."
"Not true," replied McCain.
"It's absolutely true," Obama shot back.
Though the issue of campaign attacks drew attention, it was not the first point in the debate where the candidates clashed. After another dismal day on Wall Street, McCain and Obama began the debate by discussing how each of their plans would best relieve the pressure on ordinary Americans.
Obama stressed a "rescue plan for the middle class," and McCain pushed his plan to buy bad mortgages from struggling families.
McCain said his mortgage plan would help "reverse this continued decline in home ownership" -- but Obama called the plan a potential "giveaway to banks."
Both candidates said taxes need to be cut, but diverged on who would best benefit from a break.
McCain cited the case of "Joe the plumber," a small business owner who confronted Obama on the campaign trail this past week, and would not be eligible for tax cuts under Obama's proposal because he earned more than $250,000 per year. McCain said Obama's tax plan fostered "class warfare."
Outside Toledo, Ohio, Sunday, Obama was approached by "Joe the plumber," who actually goes by the name Joe Wurzelbacher, a big, bald man with a goatee who asked Obama if he believes in the American dream.
"We're gonna take Joe's money, give it to Sen. Obama and let him spread the wealth around," McCain said. "Why would you want to increase anybody's taxes right now?"
Obama countered by suggesting tax cuts for the wealthy were "the centerpiece" of McCain's tax proposals.
"Tax policy is a major difference between Sen. McCain and myself," Obama said. "We both want to cut taxes, but differ on who we want to cut taxes for. Sen. McCain wants to cut taxes for some of the biggest companies in America."
As the discussion moved to how to cut spending, McCain got in an early zinger.
In an effort to rebut Obama's continued efforts to tie his policies to the unpopular incumbent president, McCain said, "I am not President Bush. If you wanted to run against President Bush, you should have run four years ago."
Obama responded, "Occasionally, I have mistaken your policies for George Bush' s policies because, on the core economic issues ... you have been a vigorous supporter of President Bush. You've shown commendable independence on some key issues, like torture, for instance, and I give you enormous credit. But essentially, what you're proposing is eight more years of the same thing."
Later in the debate, the candidates tangled on the hot-button issue of abortion.
Though Obama and McCain disagreed on whether they believed the historic Supreme Court decision on abortion, Roe v. Wade, was right, they both said they would not use abortion as a "litmus test" for choosing potential nominees to the court.
"I have never imposed a litmus test on anyone," McCain said. "I thought [Roe] was a bad decision. I think the decision should rest in the hands of the states. I believe we should have nominees based on qualifications rather than litmus test."
McCain also accused Obama of being out of touch with the "views of mainstream America" by refusing to oppose legislation aimed at late-term, or partial-birth, abortion during his time in the Illinois State Senate.
"Let me talk to you about an important aspect of this issue: We have to change the culture of America -- show courage and compassion," McCain said. "Obama, as a member of the Illinois State Senate, voted against a law that would provide immediate medical attention to a child. He voted present on another vote where he voted against a ban on partial-birth abortion. I don't know how you vote present on some of that. That's his record, and that's a matter of his record. ... It was clear-cut votes that Obama voted in direct contradiction to the feelings and views of mainstream America."
Obama said he opposed legislation calling for a ban on late-term abortions because there was no exception to protect the life of the mother.
"If it sounds incredible that I would vote to withhold life-saving treatment from an infant, it's because it's not true," Obama said. "I support a ban on late-term abortions as long as there's an exception for a mother's health and life, and there was no exception. That was rejected and that's why I voted present. I'm willing to support such a bill as long as there's that exception."
The debate was expected to feature the most fireworks of any of the three face-to-face confrontations between McCain and Obama, and it did not disappoint.
Earlier this week, McCain's growing deficit in the polls led him to vow to "whip his [Obama's] you-know-what."
An ABC News/Washington Post poll showed Obama with a 10-point national lead. A New York Times/CBS News poll put that deficit at 14 points.
ABC News' Jake Tapper contributed to this report