The key question about cloture isn’t asked here, but that would be the next step. Ben Nelson is suggesting that his vote to advance the health care bill is dependent on getting a Stupak amendment.

A key Senate centrist is “highly unlikely” to support any heath bill without an abortion provision similar to the House’s Stupak amendment.

A spokesman for Sen. Ben Nelson (Neb.) said the centrist Democrat was pleased by the amendment, offered by Rep. Bart Stupak (D-Mich.), which was included in the House health reform legislation to restrict federal funding for abortions [...]

“This is a very important issue to Sen. Nelson and it is highly unlikely he would support a bill that doesn’t clearly prohibit federal dollars from going to abortion,” Thompson said.

I don’t expect Ben Nelson to support a health care bill in practically any form. The key question is whether or not he would join a Republican-led filibuster. That’s what needs to be asked of him.

Meanwhile, the White House started off as Switzerland today, without wanting to weigh in on one side or the other, but the President himself said this today.

TAPPER: Here’s a question a lot of Senate Democrats want to know. You said, when you gave your joint address to Congress, that under our plan, no federal dollars will be used to fund abortions. This amendment passed Saturday night which not only prohibits abortion coverage in the public option, but also prohibits women who receive subsidies from taking out plans that — that provide abortion coverage. Does that meet the promise that you set out or does it over reach, does it go too far?

OBAMA: You know, I laid out a very simple principle, which is this is a health care bill, not an abortion bill. And we’re not looking to change what is the principle that has been in place for a very long time, which is federal dollars are not used to subsidize abortions. And I want to make sure that the provision that emerges meets that test — that we are not in some way sneaking in funding for abortions, but, on the other hand, that we’re not restricting women’s insurance choices, because one of the pledges I made in that same speech was to say that if you’re happy and satisfied with the insurance that you have, that it’s not going to change. So, you know, this is going to be a complex set of negotiations. I’m confident that we can actually arrive at this place where neither side feels that it’s being betrayed. But it’s going to take some time.

It will be incredibly tricky to thread that needle. Especially if Ben Nelson is out there making threats. It’s good that the President is making the statement that disallowing plans that cover abortion services in the exchanges would represent a change to women’s health care coverage. But if Nelson and Stupak team up to demand restrictive anti-choice language, they will simply be taken more seriously that threats from the opposite ends of the spectrum from the Pro-Choice caucus, because progressives and liberals have shown themselves unwilling to kill this bill time and again.

UPDATE: Nelson explicitly threatens to filibuster.

“If it doesn’t make it clear that it does not support abortion, does not pay for abortion, you can be sure I will vote against it.”

I asked Nelson if his opposition extended to procedural supermajority votes. He had a one word answer: “Yes.”

To be clear, he did not go so far as to say that he will block anything less restrictive than the Stupak amendment in the House bill. “The [less-restrictive] Capps language, we’ll continue to look at, but I think that there has to be some additional strengthening of that language,” Nelson said.

There’s some wiggle room, actually, but the filibuster threat is out there.