Another day, another development in the debate over abortion in health-care reform. This time, it’s a swing in favor of the abortion-rights side: pro-life Democrat Sens. Ben Nelson and Bob Casey Jr., both staunch abortion opponents and Stupak-amendment supporters, are toning down their demands.

It was just last week that Nelson was telling Politico he was “sure” he would not support a health-care reform bill without a Stupak amendment. But late last night, CNN put this small item on its political ticker: “Sen. Ben Nelson, D-Neb…now says he would be satisfied with the less restrictive language approved by the Senate Finance Committee.” Read: no more Stupak.

Then, there’s Casey, a reliably anti-abortion rights voice in the Senate. He voted for something similar to the Stupak amendment in committee, but since the House vote has pulled back his support, with statement’s like this one in Congress Daily:

[Casey] said he did not want to “draw lines in the sand.”

"I think it’s important we get a good strong health-care bill done this year, but I think we can get a bill done that keeps public dollars out of paying for abortion,” Casey said. “There is still some work to be done on that, even in the light of what the House did…The Senate is a different place; there are different dynamics.”

This follows on the heels of some earlier comments to the same tune.

What gives? A few things, first being Obama’s pretty clear declaration that the amendment will not make it the piece of legislation he signs. Then you have an incredibly strong mobilization of the abortion-rights community to defeat the Stupak amendment (compared with their incredibly lame lack of mobilization around the House version). And, last, you have the math, courtesy of NARAL: 41 abortion-rights senators, 40 opposed, and 19 in between. Even if rights opponents shore up middle-of-the-road senators, they’re still at least one vote shy of the 60 needed to introduce the amendment to the floor. For Stupak, the numbers don't quite add up.