Danny Hayes is an Assistant Professor of Government at American University and a contributor to Behind the Numbers.

The issue of American military action against Iran -- what we might call, thanks to Arizona Sen. John McCain, the Bomb Iran Debate -- has received renewed attention of late.

But largely missing from discussions of the public’s willingness to support such a confrontation is the role that political leaders themselves play in shaping opinion. A study Matt Guardino and I carried out this summer shows that the positions staked out by political elites -- both here and abroad -- would significantly influence public support for military action against Iran.

During last week’s GOP primary debate on foreign policy, several presidential hopefuls -- including former Massachusetts governor Mitt Romney and former House speaker Newt Gingrich -- entertained the prospect of military action if it appears to be the only way to curtail the Iranian regime’s apparent nuclear ambitions.

(On Thursday the Senate voted unanimously to impose sanctions against the Iranian Central Bank.)

While many Americans see Iran as an “ enemy ,” recent polling data shows little public support for an attack. In a CNN/ORC survey conducted days before the Washington debate, just 16 percent of Americans preferred military action over continued economic or diplomatic efforts. An earlier CBS News Poll found similar results.

But these data are limited in gauging public sentiment about military intervention were the president or other political leaders to advocate such a move. Public opinion in foreign affairs is driven not only by Americans’ own general preferences for force or diplomacy, but also by the arguments made by political leaders.

To test this notion with Iran, Guardino and I conducted an experiment in which subjects were divided into groups. Each group read different news articles describing a proposal by GOP congressional leaders for air strikes against suspected Iranian nuclear facilities. In the news stories we used -- which were designed to mimic the real thing -- we varied the positions taken by different politicians. For instance, in one version, President Obama supported the GOP’s proposal for military action. In another, he opposed it. After reading the story, subjects were asked how supportive they were of a strike against Iran.

 Not surprisingly, public support for the GOP-backed military strike was significantly higher when Obama supported the plan than when he opposed it. The graph below compares the average level of support for action against Iran (on a four-point scale) between two groups: people who read an “Obama supports” story verses those who read an “Obama opposes” version. Higher numbers indicate more support, and separate lines are plotted for Republican and Democratic respondents.

As is also true in national survey data, Republicans were more supportive of an attack, regardless of Obama’s position. But they grew less supportive when he opposed action, indicating the influence of the president in military matters, even among the opposition party. Democratic opinion was affected by Obama’s position even more strongly, as shown by the steeper slope of the blue line.

But it’s not just the views of domestic politicians that matter. We also found that opposition from U.N. Secretary-General Ban Ki-moon moved public opinion. .

Again, both Republicans and Democrats became less inclined to endorse military action against Iran when the news story reported that Ban expressed reservations about it. Democrats were actually less responsive to Ban’s opposition than their GOP counterparts, most likely because of the counter-balancing influence of Obama’s support for military action.

These findings are consistent with an emerging line of research in political science that suggests foreign voices -- officials from overseas governments and representatives of international organizations -- can shape Americans’ attitudes toward U.S. foreign policy. Conventional wisdom has held that the views of foreign actors are irrelevant for U.S. opinion. But it now appears that the sources of domestic opinion may sometimes lie across the water’s edge.

When it comes to Iran, the level of public support for military action would depend in large part on the policy positions of congressional leaders, the president, and even international elites.

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