Mitt Romney scored a hard-won, home state triumph in Michigan and powered to victory in Arizona on Tuesday night, gaining a two-state primary sweep over Rick Santorum and precious momentum in the most turbulent Republican presidential race in a generation.
Romney tweeted his delight -- and his determination: "I take great pride in my Michigan roots, and am humbled to have received so much support here these past few weeks. On to the March contests."
The two other candidates, former House Speaker Newt Gingrich and Texas Rep. Ron Paul, made little effort in either state, pointing instead to next week's 10-state collection of Super Tuesday primaries and caucuses.
Romney's Arizona triumph came in a race that was scarcely contested, and he pocketed all 29 of the Republican National Convention delegates at stake in the winner-take-all state.
Michigan was as different as could be -- a tough, expensive battle that Romney could ill afford to lose and Santorum made every effort to win.
Returns from 96 percent of Michigan's precincts showed Romney at 41 percent and Santorum at 37.9. Paul was winning 11.6 percent of the vote, compared with Gingrich's 6.5.
With 79 percent of Arizona's precincts reporting, Romney's total was 47.5 percent, Santorum's 26.3, Gingrich's 16.3 and Paul's 8.5.
Santorum was already campaigning in Ohio, one of the Super Tuesday states, when the verdict came in from Michigan.
"A month ago, they didn't know who we are, but they do now," he told cheering supporters, vowing to stay the conservative course he has set.
In Michigan, 30 delegates were apportioned according to the popular vote. Two were set aside for the winner of each of the state's 14 congressional districts. The remaining two delegates were likely to be divided between the top finishers in the statewide vote.
With his victory in Arizona, Romney had 152 delegates, according to the AP's count, compared with 72 for Santorum, 32 for Gingrich and 19 for Paul. It takes 1,144 to win the nomination at the Republican National Convention in Tampa, Fla., in August.
In interviews as they left their polling places, Michigan voters expressed a notable lack of enthusiasm about their choices. Just 45 percent said they strongly favored the candidate they voted for, while 38 percent expressed reservations, and 15 percent said they made the choice they did because they disliked the alternatives.
The lengthening GOP nomination struggle has coincided with a rise in President Obama's prospects for re-election. A survey released during the day showed consumer confidence at the highest level in a year, and other polls show an increase in Americans' saying they believe that the country is on the right track.
Not even the opening of the polls across Michigan brought an end to the squabbling. Romney accused Santorum of trying to hijack a victory by courting Democratic votes through automated telephone calls and suggested that his rival was appealing to conservatives in the state by making the kind of "incendiary" statements that he would not.
"I'm not willing to light my hair on fire to try and get support," Romney said. "I am what I am."
Santorum, a former Pennsylvania senator, brushed aside the allegations of trying to hijack support, saying Romney had made a pitch to independents in earlier states.
"We're going to get voters that we need to be able to win this election. And we're going to do that here in Michigan today," Santorum said, referring to blue-collar voters who often provide the swing vote.
Michigan provided a key test for Romney as he struggled to reclaim his early standing as front-runner in the race. The first of the industrial battleground states to vote in the nominating campaign, it is also the place where the former Massachusetts governor was born and where he won a primary when he first ran for the party nomination four years ago.
But Santorum rolled into the state on the strength of surprising victories Feb. 7 in caucuses in Minnesota and Colorado plus a nonbinding primary in Missouri.
The Michigan primary was open to Republicans or any voters who declared they were Republican for the purpose of voting, and there was precedent for an influx of outsiders influencing the outcome.
In Michigan, Santorum appeared in churches at times and often dwelling on social issues, as is his custom.
Romney made a play for tea party support, too, at a pair of appearances, but for the most part campaigned on his pledge to use his background as a successful businessman to help create jobs and fix the economy. Last week, he issued a call for 20 percent across-the-board cuts in personal income tax rates.
But he was hampered by off-the-cuff comments that reinforced his difficulty in reaching out to struggling voters in a state with 9.3 percent unemployment. He said at one point that his wife drives a couple of Cadillacs, and at another that he was friends with owners of NASCAR teams.
At a rare news conference after the polls opened Tuesday, he acknowledged that his own mistakes had hurt his campaign.