Presidential contender Mitt Romney is widely believed to have dominated in his first debate against President Barack Obama on Oct. 3, dramatically changing the trajectory of the race from a blowout loss to neck-and-neck contest.

Then a fiery Obama came back swinging in the second debate last week, scoring a win in most polls over a far less commanding Romney.

Now, with a razor-thin margin between the two candidates, and neither with any ground they can afford to lose, the candidates are gearing up for their third and final match up in Boca Raton, Fla. Monday night.

The first debate covered domestic policy, the second a town hall meeting over a range of issues. Monday night's debate focuses on foreign affairs.

Many believe it's the president's debate to lose; Obama has scored his highest approval ratings with the public on his handling of international issues, and can boast of several impressive achievements during his tenure as president, most significantly the capturing and killing of Osama bin Laden. Romney, on the other hand, has limited foreign policy experience, having spent most of his life in private equity outside of one term as the governor of Massachusetts. A trip overseas in the summer, meant to bolster those credentials, was largely panned after Romney made several statements considered offensive by the countries he was visiting. Obama is aiming to expose Romney as naive and uninformed on international affairs.

But with the events in Libya on September 11 under fire, Obama is more vulnerable on foreign issues than he has ever been, which could give Romney an opening in Monday night's debate. Romney has already been gaining ground with voters when it comes to foreign policy; though polls still show the president ahead with voters based on which candidate would handle foreign policy decisions better, Romney has been rapidly closing the gap over the last few weeks. A strong performance could tip the scales in his favor.

It's unclear how much of an impact Monday night's debate will have, with the vast majority of voters surveyed stating they have decided on a candidate. Many political analysts believe most of Romney's gains after the first debate were primarily from right-leaning independents who would have ended up voting for him regardless of his debate performance, rather than him changing voters' minds on who to elect.

Still, another dominating performance by Romney coupled with a weak one by the president could nudge Romney just enough to eke out a victory in two weeks. A draw or an Obama win could help Obama hold on to his narrow lead in pivotal swing states like Ohio, giving him a second term.

The six planned segments are: "America's role in the world," "Afghanistan and Pakistan," "The Rise of China and Tomorrow's World," "Israel and Iran," and "The Changing Middle East and the New Face of Terrorism." Each segment is supposed to last 15 minutes, but as seen in the previous two debates, it's likely some segments will go over time, and possible not every topic will be reached if an early segment takes too long.

The debate begins at 7 p.m. and will be moderated by CBS News' Bob Schieffer.