By Eleanor Clift, The Daily Beast

News outlets are busy canvassing Republican senators to see how they plan to vote Thursday on the Blunt amendment, which would allow employers to withhold insurance coverage for any health-care service that violates their “religious beliefs and moral convictions.” It would grant this exemption not only to religiously affiliated institutions but to all secular employers as well.

With less than 24 hours to go before the vote, only Maine Sen. Olympia Snowe had confirmed that she would vote against the measure. Her fellow Maine moderate, Sen. Susan Collins, remained undecided, at least for the record. A third female Republican senator, Alaska’s Lisa Murkowski, was also withholding her commitment, raising the prospect of a potential mini–women’s rebellion within the GOP over the controversial amendment.

Introduced by Missouri Republican Roy Blunt and cosponsored by Massachusetts Republican Scott Brown in the heat of the debate over making contraception coverage mandatory as part of preventive health care for women, the amendment looked like a good vehicle for Republicans seeking to make the debate about big government trampling on religious freedom. But polls have since shown that the religious-liberty argument has been undercut by successful Democratic efforts to characterize it as a war against women, and comedians portraying it as the GOP’s war against sex.

Snowe’s surprise declaration that she would be stepping down from her seat after three terms because of the “atmosphere of polarization and ‘my way or the highway’ ideologies” served to crystallize the debate over the Blunt amendment. Her decision also underscores the political peril facing Republicans over the measure. Asked about it on Wednesday, Mitt Romney told a reporter he was “not for” the Blunt amendment, but within the hour, a spokesperson came back to say the way the question was phrased was confusing, and that Romney supports the Blunt measure “because he believes in a conscience exemption in health care for religious institutions and people of faith.”

Romney won’t get off that easy, because the issue is more complicated. The Blunt amendment goes beyond religious institutions, allowing any employer that, for example, disapproves of smoking or drinking to potentially withhold treatment for those behaviors. After weeks of overreach on women’s issues, including a debate over invasive probes as part of a bill in Virginia requiring women seeking abortions to have an ultrasound, you would think that Republicans would be looking for a way to get back to the economic issues that were supposed to define this election year.

Massachusetts Sen. Scott Brown is in an especially difficult position as a cosponsor of Blunt. He really can’t back away, so instead he’s been doubling down, claiming that Sen. Ted Kennedy, his iconic predecessor, would agree with him, an assertion that Kennedy’s son Patrick says is flat wrong. The younger Kennedy asked Brown to refrain from airing a radio ad invoking his father’s name; Brown refused. Brown’s efforts to portray himself as an independent-minded lawmaker will take a big hit if he goes ahead with this vote.

A unified Republican vote has been a hallmark of Senate Minority Leader Mitch McConnell, and there was immediate speculation that Snowe’s decision to resign was driven in part by pressure from the GOP leadership to get her to vote with her party on Blunt. The fact that she gave only a few hours’ notice to McConnell and Texas Sen. John Cornyn, who heads the National Republican Senatorial Committee, fueled the speculation that Snowe, long a thorn in her party’s side, had finally had enough. A spokesman for Snowe denied that the pending Blunt vote had anything to do with her decision to resign.

Snowe’s frustrations with her party have been longstanding. Democratic Sen.  Barbara Mikulski, a friend of many years, took to the Senate floor on Wednesday to decry Snowe’s departure, saying it’s “because she’s sick and tired of the partisanship.”

For a time, Snowe voted against her party in almost equal measure with her support for Democratic legislation, but that balance was changing as she faced Tea Party pressure in a primary challenge and, in an election year, more of a concerted effort in the Senate for Republicans to stick together. She did not support President Obama’s health-care bill, though she did back the initial stimulus spending, one of only three Republicans to do so.

The respect Snowe commands on Capitol Hill and among the media is substantial, and she will be missed as one of the very few who could at least be courted across party lines. A Democrat affiliated with a Senate campaign and who did not wish to be named said of the Republicans, “They have gone off into some deep, dark cave that we came out of 400 years ago, and poor Olympia Snowe had enough.” A pro-choice Republican woman from Maine is a job description that doesn’t find many takers in today’s GOP, to the detriment of both major political parties.