TROY, Mich. -- It may just turn out that Mitt Romney's most important endorsement in his battle against Rick Santorum for the Michigan primary isn't Gov. Rick Snyder, or any of the host of legislators or local luminaries who've backed his candidacy this cycle, but instead Santorum himself - who supported Romney in 2008.
Saturday, before more than a thousand attendees of a conservative conference, Romney used Santorum's 2008 endorsement as a pivot, around which he turned from explaining his own vision to throwing a verbal haymaker at Santorum, who earlier Saturday at the same event called for the party to nominate a "consistent conservative" to take on Barack Obama.
"I can attest to my conservative credentials by quoting someone who endorsed me in 2008 campaign. Senator Santorum was kind enough to say on the Laura Ingraham show, he said, Mitt Romney, this is the guy who is really conservative and who we can trust. And when he came out and endorsed me he said these words: He said he is the clear, conservative candidate." Romney said. "He's right, I'm the conservative candidate and what we need in the White House is principled, conservative leadership and I¹ll bring it."
The audience reacted audibly here at the Americans For Prosperity conference as Romney proceeded to dissect Santorum as a creature of Washington who had sold out his principles.
"In that last debate we heard something about business as usual in Washington," Romney said. "When the senator mentioned that sometime you have to take one for the team what he was describing was the circumstances where he disagreed with something on principle but he had to vote for it because that was taking one for the team. We can't do that anymore. We can't continue to take one for the team. My team is the people of the United States of America, and I'm going to fight for that team, not for the partisans in Washington.
As the race for Michigan has tightened to a margin-of-error contest, Romney has racheted up his tactics and his rhetoric against Santorum. Saturday he delivered his most complete rebuke of the former senator's record, folding in attacks old and new, and hitting Santorum for supporting Planned Parenthood funding and Title X -- even though he claimed to be against those programs, and for funneling cash into earmark projects like the so-called "Bridge to Nowhere."
The newest line in the attack came in the form of tying Santorum to his former Senate colleague Arlen Specter, whom Santorum endorsed over conservative challenger Pat Toomey in 2004, and during Specter's run for president in 1996.
"Remember how he described how he supported Arlen Specter as an effort to get a deal to get some judges approved and then Arlen Specter said there was no such deal and he backed away from that," Romney said. "It was also 1996 when he supported Arlen Specter, by the way ... when Arlen Specter was running for president. Arlen Specter, the only pro-choice candidate we've seen in that race, there were other conservatives running like Bob Dole, he didn't support them. He supported the pro-choice candidate, Arlen Specter. This taking one for the team... that's business as usual in Washington."
Romney's address here was well-received, including at least one standing ovation, but could be a preview of a more negative race to come between Romney and Santorum. Asked after his remarks why he had taken a more aggressive approach today against Romney, Santorum told reporters he had to "fight fire with fire."