* Romney beat insurgent Santorum by eight votes

* Texas Governor Perry says may drop out

* Campaigning moves to New Hampshire for January 10 primary

MANCHESTER, NH - After his razor-thin victory in Iowa, former Massachusetts Governor Mitt Romney on Wednesday predicted "fast and furious" attacks from rivals seeking to oust him from his front-runner perch in the race for the Republican presidential nomination.

Romney edged out Rick Santorum, a conservative former Pennsylvania senator, by only eight votes in Iowa's caucuses, the first presidential nominating contest of 2012, as each received about 25 percent of the vote.

Ron Paul, a Texas congressman known for his small-government views, was a close third with just over 21 percent.

The result solidified Romney's status as the person to beat in the race to pick a challenger to President Barack Obama in November's election. But his eight-vote win over Santorum also underscored his inability to secure the trust of socially and fiscally conservative Republicans ahead of what is likely to be the most expensive presidential election campaign in history.

Newt Gingrich, a former front-runner who finished in fourth place with about 13 percent of the votes, signalled that he would campaign more aggressively against Romney, whom he has linked to a series of bruising TV attack ads.

"I know the attacks are going to come and they're going to become more fast and furious now," Romney said on ABC's "Good Morning America" on Wednesday, after eking out his 30,015 to 30,007 win over Santorum.

Gingrich called Romney a liar on Tuesday and Santorum took a stab at him as a "moderate," a dirty word to many conservative Republicans, as the Iowa results came in.

Santorum, who until recently had been little more than an afterthought in the race, was the latest in a series of candidates to benefit from Romney's weakness.

Campaigning in all of Iowa's 99 counties, he emphasized his home-schooled children and opposition to gay marriage in a bid to win the state's large bloc of Christian conservatives.

Santorum staked his campaign on a strong showing in Iowa, but with little cash and a bare-bones campaign operation he could have difficulty competing in other states.  

Romney attributed his 25 percent share of the caucus vote to the large size of the field. "This was a seven-person field, of course, and so you can't do with seven people in the field what you can do with a smaller field," he said on ABC on Wednesday.

Romney is a strong front-runner in New Hampshire, which holds its primary on January 10. A Suffolk University poll on Wednesday had Romney at 43 percent, to 14 percent for Paul and 9 percent for former Utah Governor Jon Huntsman, who has based his campaign in the small New England State.

The Suffolk poll had Gingrich at just 7 percent and Santorum at 6 percent in New Hampshire.

Texas Governor Rick Perry, who finished fifth in New Hampshire and said he was going home to reassess his campaign, had 1 percent support in the Suffolk survey. Minnesota Congresswoman Michele Bachmann was at 2 percent.

Bachmann who received 5 percent in Iowa, to finish sixth, said she is continuing her campaign.

With deep reserves of cash and a strong campaign infrastructure, Romney has the resources to compete in bigger states like Florida at the end of the month. He has been focusing his attacks on what he terms Obama's "failed presidency."

A Republican official said Senator John McCain, the party's 2008 nominee, would endorse Romney on Wednesday.

Sparsely populated Iowa yields just 25 delegates of the 1,143 needed to lock up the Republican presidential nomination, and those delegates aren't actually awarded for months after Tuesday's caucuses.

About 120,000 people participated in Tuesday's Republican vote, and another 25,000 participated in the Democratic caucus -- about 8 percent of the state's eligible voters.