WASHINGTON (AP) - Still neck-and-neck after all these months, Barack Obama and Mitt Romney head into their third and final debate with each man eager to project an aura of personal strength and leadership while raising doubts about the steadiness and foreign policy credentials of the other guy.

Each is aiming for a commanding performance Monday to settle the seesaw dynamics of the first two debates: Romney gave Obama an old-fashioned shellacking in the first round, and the chastened president rebounded in their second encounter.

The 90-minute faceoff at Lynn University in Boca Raton, Fla., offers the candidates their last opportunity to stand one-on-one before tens of millions of Americans and command their undivided attention before next month's election. Both candidates largely dropped out of sight and devoted their weekends to debate preparations, a sure sign of the high importance they attach to the event.

Romney and Obama toured the debate site Monday afternoon ahead of their evening debate in the battleground state of Florida. Their running mates were seeking votes in two of the eight other states whose up-for-grabs electoral votes will determine the next president - Vice President Joe Biden in Ohio and Republican Rep. Paul Ryan in Colorado. Also still hotly contested: Iowa, New Hampshire, Nevada, North Carolina, Wisconsin and Virginia.

Ryan told voters in Pueblo West, Colo., that the stakes are high. "We are in the midst of deciding the kind of country we're going to be, the kind of people we're going to be, for a generation," he said.

Obama's deputy campaign manager, Stephanie Cutter, said Monday that "it really now comes down to that small segment of undecided voters."

Appearing on NBC's "Today" show, Cutter said, "The ground game is incredibly important at this point. We feel pretty good about where we are."

Hours before the debate was to begin, the Obama campaign announced it was running a new television ad in the debate state of Florida with a rare focus on foreign policy. Most other television spots have been on economic and other domestic issues. The ad talked about the costs of the past decade of war over an image of a soldier with a prosthetic leg. It pointed out that Obama ended the war in Iraq and said Romney would have kept forces in the country longer to help with the transition.

Campaign surrogates went on Sunday talk shows and campaigned Monday to frame the foreign policy matters that moderator Bob Schieffer will put before the candidates in a discussion sure to reflect "how dangerous the world is in which we live," as the CBS newsman put it. Iran's nuclear intentions, the bloody crackdown in Syria, security concerns in Afghanistan, China's growing power - all that and more are on the agenda.

Biden told voters during a campaign stop in Canton, Ohio, Monday that the debates are showing the profoundly different visions each ticket has for leading the country, including the U.S. military presence in Afghanistan.

"We will leave Afghanistan in 2014, period. They say it depends," Biden said. "Ladies and gentlemen, like everything with them, it depends. It depends on what day you find these guys."

On Libya, senior Romney campaign foreign policy adviser Dan Senor said on NBC Monday that "they didn't have the proper security" at the U.S. Consulate in Benghazi where Ambassador Christopher Stevens and three other Americans were killed on Sept. 11.

On Iran, Senor said that Romney's approach is that "we've got to reach a diplomatic solution." He said the Obama administration's policy on Iran for the past four years has not discouraged Tehran from moving forward with its nuclear ambitions.

David Axelrod, a senior Obama campaign adviser, credited the president for isolating Iran within the global community and adopting effective sanctions that have crippled the Persian Gulf nation.

"For two years, the president traveled the world putting together a withering international coalition. And now the sanctions that they agreed on are bringing the Iranian economy to its knees," Axelrod said on NBC Sunday. "They're feeling the heat. And that's what the sanctions were meant to do."

The series of interviews Sunday and Monday fed into the broader debate over which candidate offers the steady hand and sound judgment for a nation facing myriad challenges at home and abroad.

Florida Sen. Marco Rubio, arguing for the Republicans, faulted Obama for "his failure to outline broad goals, real goals, a real view of what America's role in the world should be." Romney, by contrast, would "use America's role in the world as a catalyst for peace, prosperity and freedom," he said.

Ryan, campaigning in Colorado Springs, Colo., on Sunday, faulted the president for potential defense cuts and said that when adversaries "see us projecting weakness, when they see us hollowing out our military ... they think we are a superpower in decline." It was a likely preview of one of Romney's arguments in the debate.

The Obama campaign released a blistering memo from Senate Foreign Relations Committee Chairman John Kerry, D-Mass., accusing Romney of offering nothing but "endless bluster" on international issues.

"He is an extreme and expedient candidate who lacks the judgment and vision so vital for the Oval Office," said Kerry, who is considered a leading candidate to succeed Hillary Rodham Clinton as secretary of state if Obama wins a second term.

When it comes to their foreign policy credentials, both candidates have reasons for optimism and concern: While foreign policy has been a strength of Obama throughout the campaign, some recent polls show his advantage narrowing. The Pew Research Center's October poll, for example, found that 47 percent of Americans favored Obama to make "wise decisions about foreign policy," while 43 percent preferred Romney.

American University professor Jordan Tama said the difficult trick for Romney in the debate will be to challenge Obama on foreign policy without looking like he's criticizing the commander in chief, which can be off-putting to voters. Obama, for his part, must make the case that his policies are sound and his leadership strong despite ongoing challenges around the world, including unrest in the Middle East and the chaotic situation in Libya.

While foreign policy has been overshadowed during this campaign by concerns about the domestic economy and jobs at home, everything matters in a race this tight. A Wall Street Journal/NBC News poll released Sunday showed each candidate favored by 47 percent of likely voters, reflecting a boost of support for Romney following his strong performance in the first debate in early October.

With early voting under way in many states, there is precious little time for the candidates to break loose. More than 4 million Americans already have voted.