Acknowledging the controversy over his comments about vanished auto industry jobs, McCain struck a defiant note, despite his attempt to exude a sunnier stance over the last several days in Michigan.
Exit polling suggested that McCain performed decently among Michigan's independent voters, mirroring his crossover appeal from his 2000 primary win here.
His standing among independents hinted that independents and Democrats -- who are allowed to cross over and vote in the GOP primary in South Carolina -- might provide him a crucial base of support in South Carolina.
But McCain could not match Romney's solid appeal among GOP voters -- a cautionary note for a veteran politician who has long been viewed suspiciously as a maverick by many right-leaning Republicans.
By overtly appealing to independents and Democrats in Michigan, McCain may have angered core Republicans resentful of outsiders choosing their candidate, Ballenger said. And he also appeared hurt in Michigan by a light crossover vote that did not break as overwhelmingly as it did for him when he won here in 2000.
Romney's resurgence scrambles the board for Saturday's primary in South Carolina. He approaches the primary with a newly minted reputation as the economy candidate, fresh from his winning approach in Michigan of emphasizing his Massachusetts experience and his business successes.
McCain returned to South Carolina, the scene of his crushing 2000 primary loss to George W. Bush, as the Republican most steeped in foreign policy, by dint of his strong support of the military surge in Iraq and long tenure in the Senate.
Charles Black, a McCain advisor and a longtime Republican party strategist, said the campaign hoped to do well among solid Republican voters in South Carolina and in Florida, which holds its primaries Jan. 29.
With former New York Mayor Rudolph W. Giuliani now retreated to his Florida "firewall," McCain will have a clear field in speaking to South Carolina's moderate Republicans, Black said.
"He practically has a monopoly," Black said.
Huckabee arrived Tuesday afternoon in South Carolina as the candidate most attuned to evangelicals and GOP populists, talking up his Christian values and promoting a "fair tax" that would eliminate the income tax and substitute a national levy on consumption.
"There's a world of hurt out there in America," Huckabee said during a concession speech from Lexington, S.C., adding: "We'll change the tax system. And we'll also make it so that your government doesn't work against you in your job, but helps work for you, because good government ought to facilitate the free- enterprise system; it ought not to complicate the free-enterprise system."
Winless GOP candidates Giuliani and former Sen. Fred Thompson of Tennessee may have benefited slightly from Romney's win.
After three early primaries, there is still no GOP front-runner, noted Romney advisor and longtime Republican strategist Ken Khachigian.
"The victory rotation -- Huckabee, then McCain, then Romney -- underscores the openness of the race," he said.
But Tuesday's results particularly buoyed Romney supporters such as Carolyn Schmidt, 58, a hospital administrator who lives in Grosse Pointe Woods, Mich.
"If he wouldn't have won, it could have been disastrous for him," she said after listening to Romney's victory speech. "But this is going to jump-start the rest of his campaign."
Martelle reported from Bloomfield Hills, Reston from Charleston, S.C., and Braun from Romulus, Mich. Times staff writers Mark Z. Barabak in Las Vegas and Michael Finnegan in Southfield, Mich., contributed to this report.