Democrats have also mocked Romney for referring to Russia in March as the top "geopolitical foe" of the United States. He later explained his position – that Russia often stands with some of the world's worst actors – in an op-ed in Foreign Policy magazine.
But there have serious openings for Romney to make a foreign policy argument lately.
Republicans have said the administration was too slow to label the attack on the U.S. consulate in Benghazi as an "act of terror."
President Obama muted that criticism during the town hall debate last week at Hofstra University when he pointed out he had used the phrase "acts of terror" during a speech the day after the attack.
Romney was unprepared for that semantic joust and lost the moment during the televised debate, but his larger point is accurate. It took the White House and the Obama administration two weeks to publicly describe the attack as terrorism even though it is now clear that U.S. officials knew it was a coordinated attack and not an organic uprising within days.
But the Libya attack has become increasingly political. Democrats have argued that Republicans on Capitol Hill investigating the Benghazi attack released classified information. Republicans have said the attack is a symptom of a larger lack of leadership by the White House.
"This is Exhibit A of a failed foreign policy," said Sen. Lindsay Graham on Fox News Sunday. "Al Qaeda is alive and well in Libya, Iraq, Syria and the wars are not receding. And what happened in Benghazi is a case study in failure at every phase, before, during, and after. And what they did after the attack, I think is just absolutely unacceptable. They tried to confuse, delay and deny. Create a narrative this was a spontaneous event when it was not, because the truth of the matter is -- the Benghazi, Libya conflict was a death trap long in the making. And this is failed presidential leadership at its worst."
On Syria, where the strongman President Bashar al Assad has waged war on rebel forces trying to overthrow him, Republicans have criticized the White House for not doing more to arm the opposition, but it is not clear what exactly Romney would do differently. Romney does not support U.S. involvement in enforcement and a no-fly zone to restrict the Syrian government.
Romney has been vocal in accusing the president of not being close enough to Israel or tough enough with Iran, which continues to pursue a nuclear program despite harsh international sanctions. News reports Sunday of the possibility of one-on-one talks between the U.S. and Iran could add a new element to the debate. The White House denied the report and Romney would not say Sunday if he would support bilateral talks.
Israel and Iran are sticky subjects in American politics. Both candidates, for instance, say that they will not tolerate a nuclear-armed Israel. And in Florida - the key swing state where tonight's debate will take place - the issue of support for Israel carries outsized importance due to a large Jewish population. Earlier this summer, Obama signed a bill renewing U.S. military support for Israel on the eve of Romney's trip there after his stop at the London Olympics.
Other subjects to watch for tonight: China and U.S. defense spending.