Barack Obama, John McCain Face Off in Final Presidential Debate

Ahead of final debate, McCain still promises to whip Obama's "you know what."

Oct. 15, 2008— -- The final presidential debate between Sens. John McCain and Barack Obama may display the most fireworks yet as the growing odds for a beleaguered McCain make his vow to "whip his you-know-what" all the more important.

McCain, who has cast himself as the "underdog" in the race, has been unable to stop the slide in his poll numbers through the first two debates.

A New York Times/CBS News poll indicates that the Republican contender has fallen as much as 14 points behind Obama -- a lead that is also reflected in numerous battleground state polls.

Earlier this week, an ABC News/Washington Post poll showed Obama with a 10-point national lead.

"John McCain has pulled a rabbit out of a hat before over the course of his career, but this is going to be a rather large rabbit out of a very small hat," Matthew Dowd, a veteran political strategist and ABC News political contributor, told "Good Morning America" today.

Watch the Final Presidential Debate Live on ABC at 9 p.m. ET

McCain and Obama will sit face-to-face with moderator Bob Schieffer of CBS News at Hofstra University in Hempstead, N.Y.

Under such conditions, it will be difficult for the candidates to avoid looking each other in the eye if and when they swap criticism and attacks.

McCain was egged on by supporters last Friday who told the Republican candidate, "We want you to fight at your next debate." McCain replied, "I think I just got my marching orders."

McCain has suggested it's likely the subject of Obama's relationship with William Ayers, the 1960s radical and co-founder of the domestic terrorist group the Weather Underground, will come up in the debate.

Obama expressed surprise that charges by the McCain -- such as those involving Ayers -- were not raised in the second presidential debate.

"I am surprised that ... he wasn't willing to say it to my face," Obama told ABC News' Charlie Gibson in an interview last week. "But I guess we've got one last debate. So presumably, if he ends up feeling that he needs to, he will raise it during the debate."

Terrrorist Ties, Voter Registration Controversy May Come Up in Debate

The controversy surrounding the Association of Community Organizations for Reform Now, or Acorn, a left-leaning voter registration group under investigation for voter registration fraud in several states, may also be raised in the debate.

McCain's campaign has attempted to tie the Acorn effort to Obama, who once represented Acorn.

"Acorn is tampering with America's most precious right. There has to be a full and complete investigation," McCain said during a campaign stop in Florida.

"Given the extensive relationship between Barack Obama and Acorn, our campaign also feels that Sen. Obama has a responsibility to rein in Acorn's efforts and to work aggressively against wide-scale voter fraud," the McCain campaign said in a statement today.

Stakes High in Final Obama-McCain Showdown

Obama can take the more cautious approach tonight.

"For Obama, he's in a do-no-harm mode. ... His big challenge is just to avoid mistakes that become the talk of the campaign trail over the next couple of days," said ABC News' Chief Washington Correspondent George Stephanopoulos.

McCain has a much tougher job, he said.

"He does have to draw some blood on Barack Obama, but if he goes too negative he'll reinforce the impressions that have been built up over the last couple of weeks that he's the candidate on the attack," Stephanopoulos said.

Both the 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.

Even if McCain scores points over Ayers and Acorn, it may not help him enough because "voters are so focused on the economy," Stephanopoulos said.

McCain Looks to Final Presidential Debate With Obama to Change Race

Republican despair heading into the final presidential debate was evident in the letter that McCain's brother sent to the campaign and the Republican National Committee.

According to The Baltimore Sun, Joe McCain complained that the strategy for promoting his famously blunt brother has been "counterproductive," and he railed at strategists who "so tightly control the message."

Republicans insist that McCain can still win and point to Ronald Reagan's skewering of incumbent President Jimmy Carter in their lone debate to pull off a come-from-behind victory in 1980.

But McCain may face longer odds running in the shadow of an unpopular Republican president and a historic financial crisis.

"Much is out of John McCain's control. Ninety percent of the country thinks we're going in the wrong direction. President Bush is tremendously unpopular right now. The economy is so sour," Stephanopoulos told "GMA."

"He is up against a wall here, and he would be having a tough time, a very tough time even if he were running a perfect campaign," he said.

Stephanopoulos added, "There's not a whole lot he can do at this point to change the dynamic in one debate."

The final debate is McCain's last, best chance before Election Day to command a national audience and to convince America that he, and not Obama, is the right guy for the Oval Office.

"I think once the debate is held, John McCain's destiny is no longer in his hands," Dowd said.