President Obama’s most nagging challenge remains a persistently sluggish economy, but a new Washington Post-ABC News poll reveals a chink in his foreign policy armor less than 11 months before he faces voters: Iran’s nuclear ambitions.

It’s a classic sleeper issue. Less than 1 percent of Americans in the Post-ABC poll named Iran as the single most important issue in their vote for president this year, and fewer than one in four in a Pew Research Center poll released last week said they were following the latest kerfuffle over the Strait of Hormuz. Nevertheless, an overwhelming majority of registered voters take Iran’s efforts to develop nuclear weapons seriously (88 percent), according to a November poll from Quinnipiac University.

Will Iran emerge as a key factor this year? The economy and unemployment rate will almost certainly remain top issues throughout the campaign. But Obama’s Republican challengers see an opening and have already drawn parallels between weakness in the U.S. economy and Obama’s positioning with Iran. In a November debate, Mitt Romney called Iran “the gravest threat to America and the world,” and that Obama “did not do what was necessary to get Iran to be dissuaded from their nuclear folly.”

They received ammunition from a November U.N. report showing Iran has “mastered the critical steps needed to build a nuclear weapon.” Obama’s current standoff with Iran over the strategic Strait of Hormuz – including his reported request for direct talks with Iran – may also provide fodder for his challengers. There’s a risk of overreaching as well. Asked about the best approach to Iran, 65 percent of Americans chose “economic and diplomatic efforts” in a November CNN/ORC poll, compared with 16 percent supporting immediate military action; 17 percent preferred no action at all.

Republicans miffed by Paul’s anti-interventionist rhetoric – The boos Texas Rep. Ron Paul received (video) in a South Carolina debate on Monday for proposing the Golden Rule approach to foreign policy are indicative of reactions from Republicans across the country. In the new Post-ABC poll, nearly twice as many Republicans and GOP-leaning independents say Paul’s opposition to military intervention overseas is a major reason to oppose him than to support him (49 vs. 25 percent), an even more negative reaction than in December.

Paul’s anti-interventionist views do have an audience in the Republican electorate, as evidenced by the cheers Paul received after declaring “This country doesn’t need another war, we need to quit the ones we’re in.” While most rank-and-file Republicans disagree with Paul on these issues, more than one in three Republican-leaning independents say his opposition to foreign intervention is a major reason to support him. Even among this group, though, more than four in 10 take the opposite view.

The poll was conducted by telephone Jan. 12-15, 2012, among a random sample of 1,000 adults. The overall results have a margin of sampling error of plus or minus 3.5 percentage points. The sample of 414 Republicans and GOP-leaning independents has an error margin of plus or minus 5.5 percentage points.

Foreign policy Wednesdays: Most Wednesdays we will feature a special poll watcher analysis of American public opinion on foreign policy. The series will be cross-posted at Foreign Policy Magazine’s Election 2012 channel .

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