(Todd Spangler and Dawson Bell/Detroit Free Press)-

Mitt Romney and Rick Santorum made moves in their past political lives that could put them at odds with a more conservative Republican base in a national campaign. The question is: Which will pay more?

 Romney approved a health care reform bill that looks a lot like the Democrats' version but argues persuasively that it has enjoyed a measure of success in Massachusetts, where he was the GOP governor of a strongly Democratic state. And he says he never intended for it to be a national model, promising to overturn the Democrats' national bill.

Santorum, as a Republican senator from Pennsylvania -- another state with deep ties to the Democratic Party and labor -- voted against right-to-work legislation and, in a different era of federal spending, for budget bills rife with earmarks. But he rightly points out that, compared with many, he kept a hold on the federal purse strings.

The fact is that both are conservative and share campaign platforms that look a lot like the others'. But with the Michigan primary looming Feb. 28 (and Newt Gingrich and Ron Paul absent so far from the state), both they and their supporters are lobbing political charges, hoping to sway voters.

Today, the Free Press analyzes how Romney and Santorum stand up to scrutiny in what they and their opponents are saying.

More Details: Gingrich, Paul say they'll visit Michigan, too

Last week, Mitt Romney and Rick Santorum had Michigan all to themselves.

Newt Gingrich and Ron Paul have plans to campaign in Michigan before the Feb. 28 presidential primary, but neither campaign had details.

Gingrich, the former U.S. House speaker, told two radio interviewers Friday that he will come to Michigan, but no dates appear on his schedule. The campaign of Paul, a Texas congressman, said he'll be in the state Saturday through Feb. 27. The appearances haven't been firmed up.

Santorum, a former U.S. senator from Pennsylvania, is expected in Michigan on Monday for an 8 p.m. appearance at Hillsdale College. Michigan native and former Massachusetts Gov. Romney will be back Friday to speak to the Detroit Economic Club, although his campaign is making plans for visits earlier this week.

Meanwhile, only Romney and Santorum and their Super PACs have purchased TV network ad time so far.