NOVI, Mich. — Overcoming his own stumbles and what he called one opponent’s “dirty trick” campaign, Mitt Romney swept both the Arizona and Michigan primaries on Tuesday, once again taking control of the Republican presidential race and earning valuable momentum as the field prepares for Super Tuesday next week.
In winning Michigan, Mr. Romney claimed victory in the state where he was born and where his father served as governor — and avoided what would have been an embarrassing loss.
And in both Arizona and Michigan, he improved on his showing from 2008, breaking what had been a trend of shedding support from his prior run.
Shortly after the networks projected Mr. Romney’s victory, his supporters broke into cheers at his victory party, and Martha and the Vandellas’ Motown hit “Dancing in the Streets” began playing.
“What a win. This is a big night,” Mr. Romney said. “We didn’t win by a lot, but we won by enough. That’s all that counts.”
With 88 percent of precincts report in Michigan, Mr. Romney had 41 percent of the vote to former Sen. Rick Santorum’s 38 percent. In Arizona, with 76 percent of precincts reporting Mr. Romney led 48 percent to 26 percent.
Rep. Ron Paul of Texas and former House Speaker Newt Gingrich trailed in both states, and they had already headed east to prepare for contests on Super Tuesday on March 6, vowing to try to extend the nomination battle all the way to the convention in Tampa, Fla., in August.
“We came into the backyard of one of my opponents, in a race where everyone said, ‘Well, just ignore [the state], you really have no chance,’ ” Mr. Santorum said at his post-election party in Grand Rapids, Mich. “The people of Michigan looked into the hearts of the candidates, and all I have to say is, ‘I love you’ back.”
Arizona’s 29 delegates to the nominating convention in August all go to Mr. Romney, while Michigan’s 30 delegates will be divided proportionally and among congressional districts. With his strong showing in Michigan’s rural areas, Mr. Santorum will likely grab a decent chunk of those delegates.
That’s some consolation for the former senator from Pennsylvania, who swept caucuses in Colorado and Minnesota and Missouri’s nonbinding primary on Feb. 7, establishing himself as the chief opponent to Mr. Romney.
Both men appeared to retool their messages in their remarks Tuesday to address weaknesses.
Mr. Romney used his victory speech to train fire at the Obama administration, saying that the president has embraced policies that have added to the national debt and failed to improve the nation’s employment picture.
“You’ve heard the saying, ‘I need a vacation from this vacation?’ Well, we need to recover from this so-called ‘recovery,’” Mr. Romney said, sparking applause and laughter from the crowd.
With his wife, Ann, and son, Tagg, at his side, he said the 2012 election is about “saving the soul of America” and will offer voters a stark contrast in governing philosophies.
“President Obama is making the federal government bigger, burdensome, and bloated. I will make it simpler, smaller, and smarter,” he said.
He vowed to cut taxes and to balance the federal budget, as well as repeal the president’s new health care law, restore the nation’s AAA credit rating and approve the controversial Canada-to-Texas Keystone XL oil pipeline, which the Obama administration rejected.
“This election will come down to two very different visions for our future,” he said. “It’s a choice between becoming a nation of and by Washington and remaining a nation of and by a free people. A choice between an entitlement society and a land of opportunity. A choice between squandering America’s promise and restoring that promise for future generations.”
For his part Mr. Santorum, who lost Michigan chiefly by losing the female vote there, spoke extensively about his mother, who he said earned a college degree when that was rare for women.
He also focused heavily on his economic message of rebuilding manufacturing, which had helped him win in Iowa and Minnesota earlier this year, but which he got away from during the weeks leading up to Michigan.
Mr. Romney also won despite self-inflicted wounds, including struggling to explain his stance on the bailout of the auto companies that began under President George W. Bush and was expanded by President Obama.
Mr. Romney said the companies should have gone through a structured bankruptcy before being able to tap federal money — though many Michigan voters view Mr. Obama’s moves as a success that has revitalized the industry.
Democratic National Committee Chairwoman Debbie Wasserman Schultz said Mr. Romney has damaged himself should he be the eventual nominee.
“He has moved far to the right in an obvious effort to pick up support from extreme tea party voters,” she said in a statement. “In Michigan, that meant doubling down on his incredibly out-of-touch position that we should have ‘let Detroit go bankrupt.’ In Arizona, it was confirming that he’d be the most extreme nominee in recent history on immigration.”
Mr. Santorum, who had led in the polls here as late as last week, seemed to stumble himself. In a debate in Arizona last week, Mr. Romney attacked him as unprincipled, and then Mr. Santorum this weekend accused Mr. Obama of being a “snob” for urging all students to aim for a college degree.
And even as he was arguing he was the conservative candidate in the race, he sought to expand his support beyond traditional Republican voters, using robocalls to urge Democrats to turn out and vote for him.
Mr. Romney called that a “dirty trick,” but Mr. Santorum said he’s just doing what Mr. Romney did in New Hampshire, when he won that state’s primary in part because of support from self-identified Democrats and independents.
“So, when he goes out and recruits 53 percent of the voters in New Hampshire who are not Republicans, that is OK?” Mr. Santorum said as he campaigned for votes on Tuesday.
The point of the robocall, he said, was to prove that he could pull together the same sort of blue-collar conservative Democratic coalition that had been part of the Reagan coalition in the 1980s.
“You can’t win Michigan or Pennsylvania unless we are able to get conservatives who don’t necessary vote with us all the time to join us in the race,” he said.
Exit polling conducted by the Associated Press and broadcast networks found that 9 percent of voters were self-identified Democrats, which was more than in 2008, but less than in the 2000 primary here.
In Arizona, Mr. Romney won in nearly every demographic group.
But in one worrisome sign for him, exit polling showed he won just 33 percent of the Hispanic vote in Arizona — well behind his share of the vote there overall. Mr. Santorum, meanwhile, picked up 31 percent.
Voters backing Mr. Santorum said he appealed to them as a conservative they could relate to.
“He’s conservative and seems to have his feet planted on the ground well. I don’t get that sense from Romney when I hear him speak,” said Karen Lanning, a 64-year-old retiree from Jenison, Mich. “When I hear him speak, I don’t know that he really has the heart for the common man. It is a total disconnect, whereas Santorum, you feel that connection.”
Mr. Romney, meanwhile, was winning over voters who said their chief concern was selecting a candidate who could beat Mr. Obama in November.
That view won him the support of Arizona Gov. Jan Brewer over the weekend, and of voters like Bob Merrill, a 27-year-old insurance agent from Portage, Mich., who said the election was about “electability.”
“There are a lot of young voters that are one-issue voters. They will vote against a guy that campaigns against abortion,” Mr. Merrill said. “Someone like Rick Santorum chooses to separate himself from Mitt Romney on socially conservative issues, which is great in a primary when you are trying to out-Republican the other person, but when you go into the general election and you need those moderate voters, it is not going to help at all.”
• Stephen Dinan reported from Tempe, Ariz.