COLUMBIA, S.C. - Mitt Romney, fresh from a strong victory in New Hampshire, turned his attention Wednesday to the southern state of South Carolina where he is perceived as too moderate and faces a fierce battle.

A rougher tone and a tougher ideological terrain await the former Massachusetts governor in the state where evangelicals make up the base of the Republican Party. His rivals are banking on that to stop him in his tracks, while Romney is looking to force them from the race with a four-state winning streak that cuts through South Carolina on Jan. 21 and Florida 10 days later.

Romney's opponents, however, will have to contend with his formidable campaign war chest.

Romney's campaign announced that it raised $24 million during the last three months of 2011. That means Romney raised $56 million in 2011 and underscores his huge financial advantage over his conservative rivals in South Carolina and beyond.

Romney posted a double-digit win Tuesday night in New Hampshire after winning by just eight votes the week before in Iowa. His victory was expected; Romney is the former governor of the neighbouring state of Massachusetts, has a vacation home in New Hampshire and is a frequent visitor to the state.

He conceded Wednesday that he has an uphill climb in South Carolina, where he finished fourth in 2008. In an interview on a morning television news show he said, "I don't know if we can win South Carolina."

Still, Tuesday night's victory in New Hampshire went a long way toward making him his party's choice to run against President Barack Obama in November.

Romney garnered 39 per cent of the vote, a 16-percentage point advantage over his closest challenger, Texas congressman Ron Paul. A win in South Carolina primary and then Florida could make Romney all but unstoppable.

Because of his appeal to independent voters, Romney could be the toughest potential rival for Obama, whose popularity has fallen because of the slow U.S. recovery from the Great Recession. Exit polls showed the economy was the biggest issue in New Hampshire, as it has been nationwide.

Romney emerged from that race on Tuesday night with no clear rival to challenge him as front-runner.

Paul finished second with 23 per cent, with 98 per cent of precincts reported. It was his second strong showing after finishing third in Iowa, the first nominating contest. But Paul remains a longshot for the nomination. While he has a loyal core of supporters drawn to his libertarian, small-government message, his calls for military cuts, withdrawing troops from Afghanistan and legalizing drugs puts him at odds with the Republican mainstream.

The third-place finisher, former Utah Gov. Jon Huntsman, also appears unlikely to win the nomination. He won 17 per cent after campaigning intensely in New Hampshire. But he is at the bottom of national polls. He is not as conservative as his rivals, and his role as Obama's ambassador to China does not endear him to Republicans with harsh views of the president.

Meanwhile, the three candidates most likely to draw conservative voters -- Newt Gingrich, Rick Santorum and Rick Perry -- have been struggling.

Gingrich, a former speaker of the House of Representatives, and Santorum, a former Pennsylvania senator who came within eight votes of winning Iowa, each won 9 per cent Tuesday. Perry, who considered dropping out of the race after a poor fifth-place showing in Iowa, effectively skipped New Hampshire to focus on South Carolina. He got 1 per cent of the vote.

All the candidates planned to campaign Wednesday in South Carolina. Some Republicans doubt whether Romney is sufficiently conservative given his shifting views on abortion and other social issues. Some are also wary of his Mormon faith.

In an appearance Wednesday in South Carolina, Gingrich -- who represented neighbouring Georgia in the House -- played up his regional ties, saying: "It's good to be home in the South." He also appealed to the state's evangelical and socially conservative voters, pledging to fight "anti-Christian bigotry."

But with conservatives failing to rally behind a single candidate, their votes could be divided among Gingrich, Santorum and Perry, creating an opening for Romney.

Several of Romney's rivals have made it clear that they will seek to undercut the chief rationale of his candidacy: that his experience in private business makes him the strongest Republican to take on Obama on the economy in the fall.

In recent weeks, rivals have stepped up criticism of Romney, seizing on his record at the venture capital firm Bain Capital.

Perry, for one, is accusing Romney of "vulture capitalism" that led to job losses in economically distressed South Carolina and other states. A group supporting Gingrich, who saw his once-soaring candidacy crash under a barrage of negative ads by Romney supporters in Iowa, has pledged to spend $3.4 million for anti-Romney ads.

Romney, in his victory speech, chastising his critics while acting as though he is already the nominee and directing much of his fire at Obama.

"The president has run out of ideas," he said. "And now he's running out of excuses."

The White House has already begun targeting Romney. Vice-President Joe Biden, in a video conference with party activists on Tuesday evening, cast Romney as someone who would side with the wealthy, while he and Obama "have one overarching commitment -- to give the middle class a fighting chance."

Obama, running unopposed, won the Democratic primary in New Hampshire.