As Mitt Romney's frontrunner status solidifies in the race for the GOP presidential nomination, his fellow Republican candidates are increasingly taking aim at the former Massachusetts governor. His decision not to sign an anti-abortion pledge last week is one issue in particular that several other Republican presidential candidates are using to target Romney.

Politico published a story this morning framing the new reality of the Republican race to face President Barack Obama in the 2012 general election: right now it basically boils down to Romney and the also-rans.

"(Romney) has built up a solid early lead and looks as strong as ever; now, the burden of closing that gap falls to a group of relatively untested, unknown rivals who have yet to prove themselves on the national stage. … To dislodge Romney, one or more of those candidates will have to grow their support many times over. That's an achievable feat, but it's not an easy one — and it's possible that none of Romney's low-profile challengers will be up to the job."

A Fox News piece published Monday relates that, earlier this month, the pro-life group Susan B. Anthony List started circulating an anti-abortion pledge that allows Republican presidential candidates to promise "to support only judicial nominees who are pro-life, to select pro-life cabinet members, to stop taxpayer funding of abortions, and to support a bill that would ban abortions after 20 weeks of pregnancy." The Boston Globe reports today that "the newly minted pledge … has been signed by five GOP candidates: U.S. Representatives Michele Bachmann of Minnesota and Ron Paul of Texas; Newt Gingrich, former House speaker; Tim Pawlenty, former governor of Minnesota; and Rick Santorum, former senator of Pennsylvania."

Per Fox News, Bachmann's campaign released a statement deriding Romney's decision to abstain from the anti-abortion pledge: "The excuses for not signing clearly continue the doubts about his leadership and commitment to ending the practice of abortion — particularly for a candidate who ran as pro-choice for the Senate and governorship of Massachusetts."

The Globe piece provides context for why Romney opted against signing the pro-life document: "Romney insists that his antiabortion credentials are rock-solid, but that he couldn't sign the pledge because it would cripple hospitals dependent on federal payments such as Medicare and tie his hands as president."

Seeking to deflate the controversy, Romney penned a first-person declaration Saturday for the conservative periodical National Review titled "My Pro-Life Pledge" in which he lays out his stance on abortion point-by-point. The opening line: "I am pro-life and believe that abortion should be limited to only instances of rape, incest, or to save the life of the mother."

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