Though few Americans want to turn their backs on global crises, they are increasingly doubtful that an America that's always in the lead benefits them or the rest of the world, the polls show.
"There's dramatically more isolationist sentiment than there's been for some time," said Andrew Kohut, president of the Pew Research Center, which conducts extensive opinion polls.
Kohut compared the current mood to periods after World War I, the Vietnam War and the Cold War, when many Americans demanded sharp cuts in military spending and fewer foreign adventures. Though Americans want the nation to lead the world, they're more focused on challenges on the home front.
Political leaders "are not nearly as cautious as people would like them to be on foreign involvements," said Christopher Preble, foreign policy director at the Cato Institute, a libertarian think tank in Washington that advocates a more limited U.S. role abroad. "The gap is considerable."
A majority of Americans has concluded that the "Arab Spring" revolutions aren't likely to benefit ordinary Arabs, and that U.S. officials should align with friendly authoritarian leaders like former Egyptian President Hosni Mubarak rather than try to spread democracy, Pew surveys have found. During the debate Monday night, Romney said he agreed with Obama's decision to urge Mubarak to step down last year amid Egypt's widening pro-democracy protests.
It has been an article of faith of Republican and Democratic administrations for five decades that America should be deeply involved in the Middle East to help protect Israel, to safeguard sources and shipments of oil, and to maintain peace in a region beset by constant tumult.
But a Pew Research Center poll this month found that 2 out of 3 Americans believe the United States should be less involved with leadership changes in the Middle East. Fewer than 1 in 4 said it should be more involved. Some 57 percent said it was more important to have stable governments in the region, even if that meant less democracy.
The poll, which surveyed 1,511 adults, found growing disillusionment with the Arab Spring revolts that have rocked much of the Middle East since early 2011. The survey found that 57 percent of respondents didn't believe the uprisings, which ousted autocratic leaders in Egypt, Tunisia and Libya and led to violence in Bahrain and a civil war in Syria, would produce lasting improvements for their populations.
Pew surveys show that the number of Americans who believe promoting democracy abroad is crucial - never high - has shrunk sharply. In 2001, 29 percent believed America should put a high priority on it; now it has dwindled to 13 percent.
Americans also have grown more jaded about U.S. foreign aid and nation-building efforts after billions of dollars were spent in Iraq, Afghanistan and Pakistan over the last decade. Pew found that 64 percent of Americans believe that countries that receive U.S. aid "end up resenting us." Only 29 percent disagreed.
Leaders of both parties, and an influential array of nongovernmental groups and think tanks, push strongly for the government to use leverage to promote human rights abroad as a moral imperative consistent with American values.
But 12 percent of Floridians believe human rights promotion is an important reason to be engaged in foreign policy, according to a poll conducted this month by the Belfer Center for Science and International Affairs at Harvard University.
In their final debate, Obama and Romney showed a sensitivity to the changing American mood. Both said they wanted to limit or avoid American military involvement in the Syrian civil war, and promised to remove the last U.S. combat forces from Afghanistan by the end of 2014 - although they agreed they might need to use military force if Iran does not curb its nuclear program.
But they also made clear they view the U.S. as the "indispensable nation" for dealing with world conflicts.
To be sure, some Americans remain deeply committed to a fully engaged foreign policy, including advocates for improved trade, human rights, a strong defense and allies with strong ties to the United States, such as Israel. Their supporters lobby on Capitol Hill and provide important political and financial support to candidates.
But polls show the issue is not a high priority for most voters.
"Candidly, the risk is not great," Preble said. "Foreign policy issues don't win elections."