COLUMBIA, S.C. -- Mitt Romney says he's ready for an uphill climb in South Carolina after coasting through New Hampshire. As the Republican presidential contest moves south, his rivals are sharpening their attacks and hoping to win over tea partyers and religious conservatives who feel uncomfortable with the front-runner.

Still, Romney continued to project a confident style Wednesday that must be wearing on his five opponents. He dismissed much of their criticism as stemming from desperation. And he said that while several can raise enough campaign money to keep the nomination fight going, "I expect them to fall by the wayside eventually for lack of voters."

Despite the rougher tone and tougher ideological terrain ahead, the former Massachusetts governor is looking to force his opponents from the race by achieving a four-state streak with victories in South Carolina on Jan. 21 and Florida 10 days later. He posted a double-digit win Tuesday night in New Hampshire after a squeaker the week before in Iowa - making him the first non-incumbent Republican in a generation to pull off the back-to-back feat.

"Tonight we celebrate. Tomorrow we go back to work," Romney told a raucous victory party in Manchester, N.H., probably mindful of the minefields that South Carolina held for him four years ago when he failed to win over Republicans skeptical of his Mormon faith and reversals on some social issues. "We are asking the good people of South Carolina to join the citizens of New Hampshire."

All the candidates planned to campaign in the state Wednesday. Romney, former House Speaker Newt Gingrich, ex-Pennsylvania Sen. Rick Santorum, Texas Rep. Ron Paul and former Utah Gov. Jon Huntsman were flying in from New Hampshire. They'll join Texas Gov. Rick Perry, who didn't invest much time in New Hampshire while putting his post-Iowa focus on South Carolina.

Several of Romney's rivals have made clear 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 President Barack Obama on the economy in the fall. Perry, for one, is accusing Romney of "vulture capitalism" that led to job losses in economically distressed South Carolina.

Romney said his opponents sound like Democrats attacking the free enterprise system and encouraging jealousy toward the wealthiest 1 percent of Americans.

"It's a very envy-oriented attack," he said Wednesday on NBC's "Today" show.

Romney said the criticism of his past dealings actually works to his benefit by highlighting the business acumen that will help him set the nation's economy right and shrink the federal government.

TV ads already are filling the airwaves, including negative spots like a new one from Gingrich assailing Romney for switching his position on an issue that resonates strongly with evangelicals who make up the base of the GOP here.

"He governed pro-abortion," the Gingrich ad says. "Massachusetts moderate Mitt Romney: He can't be trusted."

About $3.5 million already has been spent on TV ads in South Carolina, the bulk of it by Perry and a supportive super PAC. But that doesn't count the $3.4 million a pro-Gingrich group has pledged to spend to go after Romney, or the $2.3 million a pro-Romney group plans to spend in the coming days. Santorum and a super PAC friendly to him also are pouring money into the state, as is an outside group working on Huntsman's behalf.

Expect a flood of more hard-hitting commercials - primarily aimed at the front-runner - in a state known for brass-knuckled Republican politics.

Romney, for his part, is dismissing the attacks, most notably the ones over his time at Bain Capital.

"President Obama wants to put free enterprise on trial. In the last few days, we have seen some desperate Republicans join forces with him," Romney said in his victory speech, chastising his critics while acting as though he is already the nominee. "This is such a mistake for our party and for our nation."

"The country already has a leader who divides us with the bitter politics of envy," Romney added.

For all of Romney's challenges, the presence of a cluster of socially conservative candidates fighting to be his chief alternative could work in his favor by splitting the vote on the party's right flank. Santorum, Gingrich, Perry and others split the faith-focused vote in Iowa. South Carolina also has a large contingent of evangelical voters, some of whom remain suspicious of Romney.

"I don't know if we can win South Carolina, I was fourth there last time I ran," Romney said Wednesday on ABC's "Good Morning America. "I know it's an uphill battle."

But Romney noted that he carried the conservative and tea party vote in South Carolina.

Unlike New Hampshire, South Carolina could end up being the last stop for some candidates.

Perry, for one, has had back-to-back dismal showings, and is dismissing the earlier contests as inconsequential as he looks to right his struggling campaign in South Carolina.

"They kind of start separating the wheat from the chaff, if you will," Perry told a cafe crowd Tuesday. "But South Carolina picks presidents."

Gingrich, the former Georgia lawmaker, is also playing on his regional ties.

"The ideal South Carolina fight would be a Georgia conservative versus a Massachusetts moderate," he said, echoing a theme central to his fierce ads.

Santorum and Huntsman also have vowed to press on in the face of Romney's latest victory. Santorum wants to claim the conservative mantle; Huntsman eschews ideological labels and is selling himself as someone who can heal a polarized nation.

"Third place is a ticket to ride, ladies and gentleman," Huntsman boomed from the lectern after finishing third in New Hampshire. "Hello, South Carolina."

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Associated Press writers Shannon McCaffrey and Beth Fouhy in New Hampshire and Connie Cass in Washington contributed to this report.

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