It sounded weeks ago like a mismatch.

The final presidential debate would focus on foreign policy — a sitting president who’d overseen the death of Osama bin Laden pitted against a one-term governor, so new to diplomatic thinking that he’d managed to offend a good chunk of Britain during a brief trip this summer.

Monday night’s debate doesn’t look like a mismatch anymore.

Instead, when President Obama meets Republican challenger Mitt Romney in Boca Raton, Fla., he will face an opponent who has already made up tremendous ground on the subject by criticizing Obama as weak, waffling and distracted by his reelection goals.

Before the two men first debated on Oct. 3, Obama held a 15-point lead over Romney on the question of who is more capable of managing foreign affairs. After Obama’s listless performance, a Pew Research Center poll found that the gap had narrowed to a slender four points.

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On Monday, the two candidates will share a stage for the last time. The race could not be closer: On Sunday, a new NBC News/Wall Street Journal poll found the candidates tied, each with 47 percent of likely voters. Before the debates began, Obama led the same poll by three points.

In this debate, Obama could face the opposite of the situation many envisioned weeks before. Instead of lending him credibility, his commander-in-chief role could make him more vulnerable, opening Obama to questions about a range of unresolved crises.

Romney is likely to renew criticism of the Obama administration’s reaction to a Sept. 11 attack that killed four Americans at a mission in Benghazi, Libya. And Obama also is likely to face questions about the civil war in Syria, a recent assassination in Lebanon and possible signals that Iran may be willing to bargain over the future of its nuclear program.

The White House on Saturday denied a New York Times report that said the United States and Iran had agreed in principle to hold one-on-one talks about that program. The report said Iran wanted to wait until after the election for talks to begin.

“It’s not true that the United States and Iran have agreed to one-on-one talks or any meeting after the American elections,” White House spokesman Tommy Vietor said in a written statement. The Reuters news service reported that Iran also had denied the report.

Libya’s political risks

Foreign policy questions played a significant role in the last presidential debate, held last Tuesday on Long Island. Romney was caught flat-footed with an overly broad statement that Obama had taken two weeks to label the attack in Benghazi an “act of terror.”

Romney was corrected by moderator Candy Crowley: Although Obama did not directly call the attack terrorism the next day, he did say that the United States will not retreat from “acts of terror.”

Since then, Romney has said little about Libya on the campaign trail. Advisers, who spoke on the condition of anonymity to discuss internal campaign thinking, said Romney has deliberately turned his focus away from Libya and toward the domestic economy and gas prices since the last debate.

His arguments on those issues had polled well among debate viewers last week, the advisers said. But Libya is almost certain to come up again Monday night.

Romney’s advisers have said data they have collected from focus groups in the swing-state of Ohio suggest that voters, especially women, think Obama is hiding something on Libya.

Romney’s allies are making that point already, raising questions about the administration’s shifting explanations of the Benghazi attack and the failure to offer greater security for American workers there.

In an Internet ad released last week, the super PAC American Crossroads used the classic language of a Washington scandal: “What did the president know and when did he know it?”

Obama seems to have prepared more for the question, which he essentially dodged in the last debate. He may have previewed his answer Thursday on “The Daily Show.”

“We weren’t confused about the fact that four Americans had been killed,” Obama said. “I wasn’t confused about the fact that we needed to ramp up diplomatic security around the world right after it happened. I wasn’t confused about the fact that we had to investigate exactly what happened so it gets fixed. And I wasn’t confused about the fact that we’re going to hunt down whoever did it .”

Obama may also try again to portray Romney as politically calculating for using the fatal attack to score points. He may also seek to make the case that Romney is unschooled in the sophisticated intelligence provided to presidents or the heavy decisions expected of them.

Senate Democrats picked up that theme over the weekend, criticizing the release by House Republicans of security details about U.S. diplomatic operations in Libya.

On Sunday, Senate Armed Service Committee Chairman Sen. Carl Levin (D-Mich.) accused Republicans of “obvious attempts to make political hay out of this tragedy,” and said the release of the names of Libyans who worked with Americans could jeopardize their lives and damage U.S. interests.

Beyond Libya, each candidate has articulated a very different role for America in the world, as the wars in Iraq and Afghanistan that defined the U.S. presence overseas for a decade are either finished or fading fast.

The challenge for Obama and Romney will be to explain their foreign policy priorities in ways that resonate with voters preoccupied with economic issues and a growing national debt that undermines the country’s ability to act abroad.

Targeting China

China heads the list of issues that straddle foreign and domestic concerns, and both candidates are likely to steer discussion of the country’s rising economic influence to the American economy.

Last week, Romney called China a “cheater” and said that on the first day of his administration he would brand China a “currency manipulator.” That is a mostly symbolic snub, but one with possible trade repercussions.

Romney said the designation would “allow me as president to be able to put in place, if necessary, tariffs where I believe that they are taking unfair advantage of our manufacturers.”

Obama and Romney have tried to score domestic political points with tough talk on China — mostly relating to lost American jobs — that skims over the complexities of the nations’ intertwined economic relationship.

Obama claimed last week that he has put “unprecedented trade pressure on China,” although he has stopped short of the steps taken by the last Democratic president, Bill Clinton, who did designate China a currency manipulator.

China denies it manipulates its currency for a trade advantage, although China’s central bank nudged the yuan higher against the dollar following last week’s debate.

Too much criticism could sour the delicate political relationship with China just as that country chooses a new 10-year leader, and risks reducing U.S. leverage to win Chinese support on the U.N. Security Council for tough sanctions against Iran and other policy priorities.

“The presidential campaign reflects an alarming scenario in which China-bashing has become a ritual,” China’s state-run news service, Xinhua, said Wednesday.

Both candidates are also likely to address Europe’s debt crisis, a drag on the already precarious U.S. economic recovery. Europe’s economic malaise is increasingly seen as a U.S. national security problem, and one Obama tried to blunt earlier this year with intensive negotiations with the continent’s leaders.

Looking beyond the American economy, debate moderator Bob Schieffer of CBS News may ask Romney about his contention earlier this year that Russia is the United States’ “No. 1 geopolitical foe.”

The comment was viewed by many as a Cold War relic, and Russia bristled at Romney’s pledge that if elected he would beef up a missile defense shield in Europe.

The U.S. relationship with Russia has improved in tone if not in substance under Obama, but it remains a wary partnership at best.

On Syria, Obama is likely to denounce President Bashar al-Assad, who still counts on Russian support, but pledge no new U.S. help to oust him.

Romney has said Obama has been too timid in dealing with Assad, while being too hard on Israel next door when it comes to talking peace with the Palestinians. And Romney has endorsed arming the Syrian rebels.

“In Syria, I will work with our partners to identify and organize those members of the opposition who share our values and ensure they obtain the arms they need to defeat Assad’s tanks, helicopters, and fighter jets,” Romney said in a foreign policy address earlier this month at the Virginia Military Institute.

Obama has declined to take that step, arguing that heavier weapons could inflame a civil war already spilling past its borders and end up in the hands of rebels the United States knows little about. The United States is providing communications gear and other logistical and humanitarian help, short of “lethal aid.”

Similar tacks on Iran

Romney’s policy on Iran appears very similar to Obama’s in substance. Romney has criticized Obama for failing to curtail Iran’s nuclear enrichment program, but he has favored the same set of international sanctions that Obama has secured.

Obama and Romney say Iran must not be allowed to develop a nuclear weapon, something Iran’s leadership denies pursuing. But Romney has aligned himself more closely with Israel’s shorter timeline for acting against it, saying he would deny Iran the “capability” of developing a nuclear weapon.

During an address last month at the U.N. General Assembly, Obama repeated his view that there is still time to negotiate with Iran. But he has not endorsed Israeli Prime Minister Benjamin Netanyahu’s appeal for a global “red line” for military intervention.

Former Pentagon undersecretary Michele Flournoy, an Obama campaign adviser, said the debate is an opportunity for Obama to showcase national security experience Romney does not have.

“We’ve seen that Romney does not hesitate to look for opportunities to use crises like Libya for political gain,” Flournoy said.

Obama can also point out that Romney has offered few policy prescriptions that differ from Obama’s, she said.

Romney has suggested that he might relax Obama’s strict timeline for withdrawing troops from Afghanistan in 2014, after 13 years of war, but has said little about how he would deal differently with Afghan leaders, the Taliban or neighbor Pakistan.

Philip Rucker contributed to this report.