Santorum pulls into third in New Hampshire poll

Rick Santorum holds a $20 dollar bill during a campaign stop at Rockingham County Nursing Home in Brentwood, New Hampshire, January 4, 2012.

MANCHESTER, New Hampshire (Reuters) - Republican presidential candidate Rick Santorum is gaining ground in the early-voting state of New Hampshire, but rival Mitt Romney still holds a strong lead ahead of Tuesday's primary.

Santorum, a former senator from Pennsylvania who finished slightly behind Romney in this week's Iowa nominating contest, rose to third place among likely primary voters, according to a 7 News/Suffolk University tracking poll released on Thursday, edging ahead of former House Speaker Newt Gingrich and former Utah Governor Jon Huntsman.

But with 8 percent of likely voters polled on January 3 and 4 supporting him, Santorum is well behind Romney, the former governor of neighboring Massachusetts who has 41 percent support. Romney polled 43 percent support a day earlier, while Santorum had 6 percent.

"Obviously Mitt Romney is at 40 percent in the polls, the chances in five days to make up a 35 or 40 point lead is going to be pretty limited but we expect to make a run and to move up in those polls and to show that we're the candidate with the momentum and we'll carry that into South Carolina," Santorum told reporters in Manchester, New Hampshire, after speaking to a local civic group.

Romney has long held the lead in New Hampshire and his challenge is to maintain that momentum after the New England contest, when the voting shifts to more conservative southern states.

Arizona Senator John McCain, the 2008 Republican presidential candidate, suggested as much in a campaign appearance with Romney late on Wednesday after endorsing his rival from four years ago.

"What you need to do, I'm asking you, is to make sure that you send him to South Carolina which such momentum that it cannot be stopped," McCain told voters.

Texas Congressman Ron Paul was second in the poll with 18 percent support, up from 14 percent a day earlier. Gingrich and Huntsman each had the support of 7 percent of likely voters, with 17 percent undecided.

The poll is based on phone interviews conducted on January 3 and 4 of 500 likely voters in the Republican primary and has a margin of error of 4.4 percentage points.

(Reporting By Scott Malone and Michelle Nichols, additional reporting by Ros Krasny; Editing by Paul Simao)