Romney is far ahead in Arizona, which also holds its primary Tuesday, but Santorumhas mounted an unexpectedly strong challenge in Michigan. Polls show a close race, and a loss would be embarrassing to Romney in the state where he was born and raised. It could jeopardize his path to victory in what's already become a prolonged fight for the GOP presidential nomination.
Romney tried to paint an optimistic picture as he campaigned in Albion. "We started what, 15 points down in the polls? Now we're leading in the polls."
He barely mentioned Santorum at his midday stop, but Monday morning Romney seized on Santorum's opinion piece in The Wall Street Journal.
"I'm glad he recognizes this is going to be a campaign about the economy," Romney said of his rival's op-ed. "It's time for him to really focus on the economy and for you to all say, `OK if the economy is going to be the issue we focus on who has the experience to actually get this economy going again?"'
In his op-ed, Santorum accused both Romney and President Barack Obama of class warfare. Santorum said Romney had undergone a "last-minute conversion" on economic solutions.
"Attempting to distract from his record of tax and fee increases as governor of Massachusetts, poor job creation and aggressive pursuit of earmarks, he now says he wants to follow my lead and lower individual as well as corporate marginal tax rates," Santorum wrote. "It's a good start. But it doesn't go nearly far enough. He says his proposed tax cuts would be revenue neutral and, borrowing the language of Occupy Wall Street, promises the top 1 percent will pay for the cuts. No pro-growth tax policy there, just more Obama-style class warfare."
If elected president, Santorum promised to approve the Keystone pipeline, review and eliminate some government regulations, overhaul the tax code, cut 10 percent of the non-defense federal workforce, balance the budget, cut spending by $5 trillion over five years and repeal Obama's health care law.
On Monday, Romney didn't mention Santorum's conservative credentials, as he had in recent days, when he tied Santorum to former Pennsylvania Sen. Arlen Specter, who supports abortion rights and switched parties from Republican to Democrat. Instead, the wealthy former Bain Capital chief stuck to his pitch as a private sector businessman.
"Senator Santorum's a nice guy, but he's never had a job in the private sector," Romney said.
At Caster Concepts. Romney nodded along with owner Bill Dobbins as he inspected the heavy duty industrial wheels the company produces.
"Are you an LLC? Are you an S-corp, are --" Romney started, trying to figure out what tax rate Dobbins' business paid. The abbreviations refer to different ways a business can be structured and taxed.
"We're an S-Corp," Dobbins jumped in, which means his business pays taxes like an individual instead of at the corporate rate -- a point Romney keeps hitting during speeches, contending that Obama wants to raise those taxes.
"Individual tax rates determine how much you put back into the business and how much goes to Uncle Sam," Romney explained, more for the benefit of the dozens of TV cameras gathered around than for the small group touring with him.
Romney at one point turned to the company's chief engineer, Elm Lee, enquiring where he got his degrees. MIT, Lee said. The Massachusetts Institute of Technology. "MIT. It's a good school," Romney said back.
Dobbins, the owner, chimed in: "Not as good as Harvard," he said to Romney, the former Massachusetts governor who has degrees in business and law from there.
At stake Tuesday are 30 delegates in Michigan and 29 in Arizona. Voting comes ahead of an intense week of campaigning across the country. March 6 is Super Tuesday, when 10 states will hold GOP nominating contests as far apart as Virginia and Alaska. Wyoming also holds county conventions beginning that day. At stake are 419 delegates to the Republican National Convention this summer -- more than have been awarded in all the previous contests combined.