A spokesman for Republican presidential candidate Newt Gingrich, R.C. Hammond, said if Gingrich had been a senator, he would have voted for the Blunt amendment. "The government doesn't have a role in dictating people's religion to them," Hammond said.

Democrats said the measure would have allowed employers and insurers to opt out of virtually any medical treatment with the mere mention of a moral or religious objection.

That effort failed, however. The Senate voted 51-48 to kill an amendment offered by Sen. Roy Blunt, R-Mo., that would have allowed employers and insurers to opt out of portions of the president's health care law they found morally objectionable. That would have included the law's requirement that insurers cover the costs of birth control.

"Fortunately, there's an effort in Washington to stop that, to reverse that," Romney said.

Addressing a town hall-style meeting in North Dakota, Romney briefly spoke in favor of the Senate provision that pitted religious freedom against women's privacy rights and riled Americans in this volatile election year. He called Obama's decision to compel insurance companies to offer contraceptive coverage -- even for employees of religious-affiliated institutions -- "an attack on the First Amendment."

The dispute offered a window into Romney's fundamental challenge in his second White House bid. He dominates his opponents with money and organization, but he has struggled to win over his party's right flank because of lingering concerns about his social conservative bona fides. The turnabout in message also allowed his critics to once again label him a flip-flopper.

The issue of contraceptive coverage resonates with conservative primary voters, but it also offers a contrast between each party's priorities that could have general election ramifications. While the issue roiled the Republican presidential contest, Obama railed against oil and gas company subsidies in New Hampshire.

"We aren't going to win with someone who doesn't excite the very people that we need to excite," Santorum said during a rally inside the New Life Assembly of God church. "We won 2010 not because we nominated moderates!"

But the damage was done. Santorum used the opening to score political points just five days before Super Tuesday's 10-state voting, suggesting that Romney was too moderate to defeat Obama in November.

Romney opened himself to criticism the day before by telling a reporter that he opposed a Republican bill to block President Barack Obama's policy on contraceptive insurance coverage. Hours later, Romney reversed himself and said he had misunderstood the question.

SPOKANE, Wash.—Seizing an opportunity to instill doubts about Mitt Romney's conservative credentials, Rick Santorum on Thursday said his presidential rival's gut reaction to a Senate measure that would have repealed mandatory health coverage for contraceptives shows the former Massachusetts governor is not conservative "at the core."

Separately, Gingrich's campaign said it was issuing an anti-Santorum "robocall" challenging Santorum's fiscal conservative record.

"As senator from Pennsylvania, Santorum cozied up to the labor bosses and voted for the AFL-CIO and against a national right to work bill that would have let workers opt out of paying union dues," say the automated call, which will go to 150,000 households in both Oklahoma and Tennessee, among the states set to vote Tuesday.

Santorum, long considered a social conservative, has risen to the top-tier in the GOP contest by welcoming opportunities to stray away from the issue voters say is their top concern: the nation's economy. At a campaign rally in Atlanta, he said Romney's "gut reaction" should have been to support the bill Republican bill.

Romney spokeswoman Andrea Saul challenged Santorum's claim of being a core conservative, saying "his `gut reaction' is to `take one for the team' instead of standing up for what he says he believes in." Saul's reference was to the former Pennsylvania senator's recent explanation that he voted for the No Child Left Behind education law, which he opposed, because politics is a "team sport" and that "sometimes, you take one for the team."

Saul called Santorum a Washington insider and said "Romney's team is the American people."

The contraceptive flap overshadowed a dispute in Michigan, where state GOP officials changed the way they award 30 delegates from the presidential primary a day after the tally showed native son Romney and Santorum each getting 15. The Michigan Republican Party Credentials Committee voted 4-2 Wednesday night to instead award 16 delegates to Romney and 14 to Santorum.

Santorum spokesman Hogan Gidley blasted the decision as a "backroom deal."

"We never thought the Romney campaign would try to rig the outcome of an election by changing the rules after the vote. This kind of back-room dealing, political thuggery just cannot and should not happen in America," he said.

Twenty-eight of Michigan's delegates were awarded based on the results in each of the state's 14 congressional districts. Two went to the winner of each district. Romney and Santorum each won seven districts, so those 28 delegates were split.

The final two delegates were supposed to be awarded proportionally, based on the statewide vote, according to a memorandum circulated by the Credentials Committee. That would result in one delegate apiece, giving each candidate a total of 15 delegates.

Instead, the credentials committee said a new rule adopted Feb. 4 was written incorrectly, and the party intended all along to give both delegates to the winner of the statewide vote -- in this case, Romney.

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Associated Press writers Dorie Turner in Atlanta and Kasie Hunt in Fargo, N.D., contributed to this report.

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