The latest national Rasmussen poll puts former Massachusetts Gov. Mitt Romney as a frontrunner heading into New Hampshire, with 29 percent of voter support.
Still, the race is close. Romney's showing in Iowa has boosted Rick Santorum's campaign, who now has 21 percent of support in the latest poll.
Newt Gingrich placed third with 16 percent.
All the candidates will square off for a debate Jan. 7 and Romney is expected to be the primary target.
Polls show Romney has a double-digit lead in New Hampshire, where voters cast their ballots in the Republican primary Jan. 10.
That lead has the former Massachusetts governor looking ahead to South Carolina, where he is campaigning alongside his latest supporter and one-time rival Sen. John McCain.
"[Romney is] an honest, straight-talking person of experience, knowledge and vision," McCain said.
Meanwhile, Romney's current opponents are on the ground in New Hampshire, and they're turning up the heat.
"We got the grassroots. We got the people," Santorum said while campaigning. "We have a lot of energy and enthusiasm. We feel very very good about this thing."
Santorum raised $1million in the 24 hours following the Iowa caucus, where he finished only eight votes behind Romney.
An ad in support of Gov. Jon Huntsman also takes aim at Romney saying, "One state can stop the 'chameleon.'"
Another ad from Newt Gingrich claims Romney's economic plan is "timid" and, "Parts of it are virtually identical to Obama's failed policy."
"If you want to truly change Washington, D.C., somebody who failed totally to change Boston may not be the right person," Gingrich said on the campaign trail.
Huntsman has spent more time in New Hampshire than any other candidate. So far, however, his campaigning hasn't translated into enough support.