Romney Wins Arizona, Michigan primaries

His victory over Mr. Santorum here in Michigan was far from commanding, but it was most likely sufficient to dampen the rising clamor from across the Republican Party about his ability to win over conservatives and connect with voters. The tussle with Mr. Santorum highlighted ample concerns about Mr. Romney, but his win spared his campaign from deep turmoil.

“I stand ready to lead our party to victory and our nation back to prosperity,” Mr. Romney told a jubilant crowd of supporters. “It’s a critical time in America.”

The victory by Mr. Romney in Arizona, which awarded him the state’s entire allotment of 29 delegates, was overshadowed by the battle in Michigan. He prevailed in the statewide popular vote by four percentage points, relying on large margins in the counties around Detroit where he spent his childhood, but the fight for delegates was closer.

Michigan awards its 30 delegates by Congressional district, which meant Mr. Santorum would either leave Michigan with nearly the same number as Mr. Romney or only slightly fewer. Mr. Santorum beamed when he took the stage before a cheering crowd in Grand Rapids and reminded his supporters of how far he had come.

“A month ago they didn’t know who we are,” Mr. Santorum said, moments after calling Mr. Romney to concede. “They do now.”

As the Republican presidential nominating fight enters its third month, the race remains far from deciding the nominee who will challenge President Obama. A dozen primaries and caucuses will take place over the next week, dominated by Super Tuesday, when more than 400 delegates will be at stake.

Representative Ron Paul of Texas spoke Tuesday evening from Virginia, a state where only he and Mr. Romney qualified for the ballot next week. Having built an extensive network of supporters in caucus states, including several holding contests on Super Tuesday, Mr. Paul pledged to stay in the race, declaring that his campaign is “still winning a lot of delegates, and that’s what counts.”

Newt Gingrich, who did not actively campaign in Michigan or Arizona, is hoping to revive his candidacy next week in Georgia and Tennessee. His allies are airing a new “super PAC” television advertisement on his behalf starting Wednesday, aggressively taking on Mr. Romney across several Southern states.

It was not an overstatement — at least in the view of many Republicans — to say that Mr. 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, Mr. Romney won the state by nine percentage points.

But after losing a string of contests to Mr. Santorum, Mr. Romney was hardly greeted with warmth and affection here. A place that his advisers hoped would offer an easy victory turned into a fierce battleground, with Mr. Santorum’s popularity among social conservatives, as well as his working-class appeal, threatening to complicate Mr. Romney’s path to the nomination.

The Republican electorate here, along with elsewhere across the country, is different from the one Mr. Romney encountered in 2008. His candidacy is facing tests that he did not go through during his first presidential bid.

In the primaries on Tuesday, the Romney campaign relied on the same coalition of voters who have consistently supported his candidacy during the seesawing series of Republican primaries and caucuses. He did best among older voters, better-educated voters and higher-income voters in Michigan and Arizona.

When Mr. Romney accepted victory, he kept his sights squarely on Mr. Obama. He did not mention Mr. Santorum or any of his rivals as he attempted to remind Republicans of his electability.

“Our campaign is about more than just replacing a president,” Mr. Romney said. “It’s about restoring the promise of America.”