WASHINGTON - A new Iowa poll shows that presidential candidate Michele Bachmann, who won the Ames Straw Poll in that state last month, now is running second to former Massachusetts Gov. Mitt Romney.

An American Research Group poll of the first-in-the-nation caucus state shows Romney leading with 21 percent. Bachmann came in second at 15 percent, closely followed by Texas Gov. Rick Perry at 14 percent.

The survey, from Sept. 22 to Tuesday of 600 likely GOP caucusgoers, has a margin of error of plus or minus 4 percentage points.

Since entering the race in August, Perry quickly shot to the top of the polls nationally, snatching up much of Bachmann's conservative base. Perry also had jumped ahead of her in Iowa.

Bachmann "has to win Iowa," campaign manager Keith Nahigian said this week. As recently as June, a Public Policy Polling survey had Bachmann at 22 percent in Florida. A similar poll released Wednesday puts her at 6 percent. In a Florida straw poll Saturday, she finished last.