The murder of the U.S. ambassador to Libya has set off a wave of confrontations — not only in the Muslim world, where protests against an amateurish film insulting the Prophet Muhammad have led to a third day of demonstrations against American diplomatic missions, but in the United States as well.

In the already hostile environment of a fierce presidential election campaign, the assassination of Ambassador J. Christopher Stevens set off a string of recriminations and finger pointing, first from Mitt Romney, the Republican candidate, directed at President Barack Obama and then from Democrats and Mr. Obama directed at Mr. Romney.

The usual, initial American reaction of rallying around the commander in chief after a tragedy was relatively short-lived, as Mr. Romney took advantage of the attack to try to strengthen his criticism of the Obama administration’s foreign policy, an area where voters — in a historical departure — give the Democratic president higher marks than his Republican challenger. Mr. Romney famously didn’t mention Afghanistan in his speech formally accepting his party’s presidential nomination last month, the first time in 60 years that a Republican presidential candidate had not mentioned war.

None of the partisan sniping should be surprising given the political climate that prevails in the United States, just 53 days before a presidential election that seems likely to be decided by a handful of states that, at this point, could go for either Mr. Obama or Mr. Romney.

But however long the customary post-tragedy American unity would have lasted in other times, Mr. Obama’s critics would have inevitably turned to the murder of Mr. Stevens and three other embassy employees in Benghazi as evidence of the administration’s faulty foreign policy.

Rudolph W. Giuliani, the former Republican mayor of New York City and past presidential aspirant, said Mr. Obama “doesn’t seem to have a really clear picture of what’s going on with the aftermath of the Arab Spring.” A foreign policy adviser to Mr. Romney called Mr. Obama’s foreign policy “fleckless.”

Others said the bold actions of the murderers in Libya — killing an American envoy for the first time in decades — reflected an administration that was viewed as weak, despite Mr. Obama’s reportedly overseeing the killing of more top Qaeda leaders than former President George W. Bush, and, of course, the killing of Osama bin Laden.

The administration is being criticized from several quarters for not having a strong steering hand in events in North Africa and the Middle East after the revolts of the Arab Spring.

But from a realpolitik point of view, it is not clear whom Washington or its Western allies would like to have in power in many of these countries. Parties led by Islamists, the most popular political forces thanks in part to dictators who tried to channel popular discontent into religion instead of politics, are not Washington’s natural allies.

Mr. Obama now finds himself in an even more difficult political situation. He was already under fire from both Mr. Romney and Benjamin Netanyahu, the Israeli prime minister, for not being tougher on Iran and its nuclear program.

Many Americans — especially conservatives, but also some all-important independent and still undecided voters — will judge the president in part on how he responds to the murder of Mr. Stevens and his colleagues. If he is seen as weak, despite being the president who “got Bin Laden,” it could hurt his chances of being re-elected: just tens of thousands of votes in a few swing states like Florida, Ohio and Colorado could change the outcome of the election.

But even as the world waits to see what the administration’s response will be to the attacks in Libya and the confrontations in Egypt and Yemen, the greatest mystery is the one surrounding the hateful video that ignited the protests. My colleague Adam Nagourney, the Los Angeles bureau chief of The New York Times, details the background of both the film and at least some of its makers. Adam’s piece is a must-read.

The other battle that has already been ignited in the United States, which is certain to join with the political and policy conflagrations, is over what brands and varieties of hate are condemnable: The anger that led to — or provided the cover for — the murderous attack in Benghazi? The religious holy war that Christian extremists seek to wage on Muslims and Islam? While much of the world may view all extremism as condemnable, anything that sets up an equivalence between Christian and Muslim extremism is likely to stoke the culture wars in the United States and lead to still new confrontations.