Angus Reid Public Opinion found a sharp partisan divide on the issue.
More than half, 56 percent of Democrats, favor sanctions and negotiations with Iran but a 40-percent plurality of Republicans prefer air strikes or invasion. Independents tilt toward the Democratic view with 52 percent favoring a non-violent approach and 19 percent military force.
Overall, 5 percent say Iran is no threat and the United States should do nothing.
Three-quarters of those surveyed have an unfavorable view of Iran, more than the 72 percent who dislike North Korea and the 69 percent who don't like Afghanistan.
Angus Reid, based in Toronto, polled 1,005 members of its Springboard America panel online Dec. 16-17. The margin of error is 3.1 percentage points.