MILFORD, Mich. -- Republican presidential candidate Mitt Romney tried to upend Rick Santorum's image as a principled defender of conservative ideals Thursday, telling voters that the former senator is just another give-and-take politician.
Romney's team believes Santorum opened himself to the attacks with a somewhat anguished explanation of his reluctant vote for a Bush-era school program in Wednesday's televised debate. Romney hoped to stop his chief rival's momentum on a day when Santorum was quietly raising money.
But President Barack Obama wasn't helping. His allies aired anti-Romney ads in Michigan while the president campaigned in Florida, a crucial swing state that GOP candidates can't afford to revisit until their nominee is settled.
A Romney setback in either Michigan's primary or Arizona's on Tuesday would be embarrassing, or worse. His campaign seemed grateful for Santorum's unsteady showing in what may have been the GOP campaign's last big debate.
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Romney pounced on Santorum's explanation for supporting President George W. Bush's "No Child Left Behind" program, now disliked by many conservatives. "It was against the principles I believed in," Santorum said in the debate. "But, you know, when you're part of the team, sometimes you take one for the team."
"I wonder which team he was taking it for," Romney said Thursday at an Associated Builders and Contractors meeting in Phoenix, before heading to Michigan. "My team is the American people, not the insiders in Washington."
Santorum also struggled in the debate to explain his congressional votes for earmarked spending and for a bill that included money for Planned Parenthood despite his "personal moral objection" to the organization, which provides abortions for low-income women. "I don't know that I've ever seen a politician explain in so many ways why he voted against his principles," Romney said Thursday.
The issue could prove troubling for Santorum, who lacks the money to match Romney's TV ads. Santorum's chief strengths include his image as a courageous social conservative willing to confront voters about the moral implications of birth control, abortion and divorce.
At a Tea Party rally in Tucson shortly before the debate, Santorum said he was "unafraid to go out and fight on all the issues we care about." He referred to Romney as "a well-oiled weather vane" that shifts with political winds.
Romney's focus on Santorum reinforced the notion that the GOP race is mostly a two-man contest heading toward the 10-state "Super Tuesday" primary on March 6. Former House Speaker Newt Gingrich campaigned Thursday in Washington state and Idaho. Rep. Ron Paul had no public events Thursday.