LIVONIA, Mich. — A day before Michigan voters decide whether to give Mitt Romney a green light toward the Republican presidential nomination, Rick Santorum continued to dismiss him as inadequate to challenge President Barack Obama in the fall.

Santorum told about 300 people at a Chamber of Commerce breakfast in this Detroit suburb that Romney was “uniquely unqualified” to be the nominee, because Romney, as governor of Massachusetts, produced a health care system similar to Obama’s.

Michigan is considered more of a prize than Arizona, which also holds a primary today, in part because Romney grew up in Michigan and a loss to Santorum would be an embarrassing blow. Analysts said the race seemed to be neck and neck. The two stand to split the 30 delegates at stake.

Romney, speaking to about 300 people at an electronics plant in Rockford, upbraided Santorum for focusing more on social issues than the economy.

“It’s time for him to really focus on the economy,” Romney said, adding it was also time for voters to consider who has more experience. “Senator Santorum’s a nice guy, but he’s never had a job in the private sector,” Romney said. “He’s worked as a lobbyist, he’s worked as an elected official, and that’s fine, but if the issue of the day is the economy, I think to create jobs it helps to have a guy as president who’s had a job, and I have.”

Santorum said the race is “about government control of your life, forcing you to buy things then forcing their values on you and your religion, which, by the way, Governor Romney did in Catholic hospitals in Massachusetts by forcing them to distribute the morning-after pill. Why would we give those issues away in this general election?”

Santorum said Romney’s tax cut plans mirror the rhetoric of Occupy Wall Street and include “just more Obama-style class warfare.”

Neither of the other contenders, Newt Gingrich or Ron Paul, has made a widespread effort in Michigan, where Paul made his third appearance Monday.

Gingrich campaigned Monday in Tennessee and said Santorum could face a far different race if he loses in Michigan. “He’s had two weeks of being the alternative” to Romney. “The fact is, I think there are profound reasons that Rick lost the Senate race by the largest margin in Pennsylvania history in 2006, and I think it’s very hard for him to carry that all the way to the general,” said Gingrich, eager for a comeback of his own.

Santorum has spent a lot of his time on the campaign trail recently talking about social issues, but he addressed the economy Monday more than he usually does, and after hearing that Romney had poked him for having failed to focus on it before, he tartly told reporters, “Tell him to read my speech.”

He cast himself as consistent and authentic, two qualities that polls suggest voters find lacking in Romney, and he suggested Romney’s economic plan consisted of tweaks on the margins.

Romney, at his event, took note Santorum had laid out his economic and tax proposal in an op-ed in The Wall Street Journal and said he was glad to see it.

“I’m glad he recognizes this has got to be a campaign about the economy,” Romney said. “It’s time for him to really focus on the economy — and for you to all say, ‘OK, if the economy’s going to be the issue we focus on, who has the experience to actually get this economy going again?’ ”

Santorum said he was “someone who can take and wage a battle on ideas, not by beating up your opponent or outspending them 10-to-1.” He said he was offering not “some minor change, not some reshuffling of the deck chairs but a real fundamental change in the size and scale of government, the role of government in your lives and the role of government in the business community.”

While he campaigned in conservative western Michigan, Romney made no reference to abortion or religious liberty, themes both men campaigned on last week.

“We need dramatic change, fundamental change in Washington,” Romney said.

“We can’t just keep on going down the road we’re on — more and more programs, spending more and more money that we don’t have. We have to say we’re going to dramatically change the structure of Washington.”

Romney has 123 delegates to 72 for Santorum, 32 for Gingrich and 19 for Paul in the Associated Press count, with 1,144 required to win the party nomination this summer at the Republican National Convention in Tampa, Fla.

The New York Times and Associated Press contributed to this article.