With the state's Republican presidential caucuses on tap for Tuesday, the CNN/Time/ORC International Poll showed Romney, the former Massachusetts governor, at 25 percent; Paul, the U.S. representative from Texas, at 22 percent; Santorum, a former U.S. senator from Pennsylvania at 16 percent; and Gingrich, a former U.S. House speaker from Georgia, at 14 percent.
The poll's margin of error is stated at plus or minus 4.5 percentage points.
Romney leads the GOP pack in New Hampshire, which has its primary Jan. 10, CNN said.
CNN said Romney and Paul each picked up 5 percentage points since a CNN/Time/ORC poll in early December. Santorum showed a quantum leap, up from 11 points, while Gingrich plummeted 14 points from the previous poll.
In New Hampshire, the CNN/Time/ORC poll shows Romney with a 44 percent share of likely GOP voters, with Paul at 17 percent, Gingrich at 16 percent, Huntsman at 9 percent, Santorum at 4 percent, Bachmann at 3 percent and Perry at 2 percent.
The margin of error is 4 percentage points for the New Hampshire results.
CNN said the polls were conducted Dec. 21-24 and Dec. 26-27 with 452 voters queried in Iowa and 543 in New Hampshire.