SOUTHFIELD, Mich. — Mitt Romney fended off a vigorous challenge from Rick Santorum in Michigan on Tuesday, narrowly carrying his native state, and won the Arizona primary on a day that revived his candidacy but did not erase the qualms conservatives have raised about his Republican presidential bid.
The victory by Romney in Arizona, which awarded him the state's entire allotment of 29 delegates, was overshadowed by the battle in Michigan, a state steeped in his family's history. The tussle with Santorum highlighted larger concerns surrounding his candidacy, but the win spared his campaign from far greater turmoil.
Before Romney could declare his victory, Santorum appeared before his cheering supporters in Grand Rapids to remind them of how far he had come. He pledged to carry the conservative fight against Romney to Ohio and other Super Tuesday states that weigh in on the race next week.
"A month ago they didn't know who we are," Santorum said, moments after calling Romney to concede. "They do now."
Rep. Ron Paul of Texas spoke Tuesday evening from Virginia, a Super Tuesday state where only he and Romney qualified for the ballot. He pledged to stay in the race.
Newt Gingrich, who did not campaign in Michigan or Arizona, is hoping to revive his candidacy next week in Georgia and Tennessee. His allies are airing a new television advertisement on his behalf starting today, aggressively taking on Romney in several Super Tuesday states.
It was not an overstatement — at least in the opinion of many Republicans — to say that Romney's candidacy was on the line in Michigan, far more than in the previous eight contests this year. He was born here, and his father, George, is fondly remembered for his service as governor nearly a half-century ago. Four years ago, Romney won the state by 9 percentage points.
But after losing a string of contests to Santorum, Romney was hardly greeted with warmth and affection. A place that his advisers hoped would offer an easy victory turned into a fierce battleground, with Santorum's popularity among social conservatives, as well as his working-class appeal, threatening to complicate Romney's path to the nomination.
Romney accepted a share of blame for his struggle to make the case that he is the party's strongest prospective nominee, but he declared, "I am who I am." He said he would not "light my hair on fire" to win over skeptical conservatives in the Republican Party.
"It's very easy to excite the base with incendiary comments," Romney told reporters Tuesday before the polls closed. "We've seen throughout the campaign that if you're willing to say really outrageous things that are accusatory and attacking President Obama that you're going to jump up in the polls."
Against the backdrop of a slowly rebounding economy, the Michigan primary offered an early test of the challenges Republicans will face when they confront Barack Obama in the fall.
The nation's most populous states, which offer the biggest cache of delegates, hold their primaries near the end of the party's nominating calendar this year, which will delay the time it takes to win the 1,144 delegates needed to secure the nomination.
"We've got four candidates all battling it out," said Romney, who is campaigning in Ohio, North Dakota and Washington state in the coming days. "This isn't going to be over in a day or two."