Democratic Sen. Ben Nelson said Thursday he won't support the Senate health bill in its current form, saying he's still not satisfied that the bill will prevent federal funding from going to abortions.

The senator from Nebraska became the focus of Democrats' efforts Thursday to rally the 60 votes they need to overcome a Republican filibuster and pass health care reform. On Wednesday, Vermont independent Senator Bernie Sanders said that "at this point" he cannot support the health reform bill, following the removal of the public option and Medicare buy-in from the bill at the insistence of Sen. Joe Lieberman.

But while Sanders highlighted progressives' disappointment with the latest version of the bill, Nelson's announcement indicated that some more conservative elements of the Democratic caucus are also unsatisfied.

"If it's not at the point where I think it needs to be with the improvements that I'm pushing -- and they've made a lot of them -- then I will not vote for cloture on the motion to end debate," Nelson told a Nebraska radio station, according to The Hill.

Earlier this month Nelson put forward an amendment to the Senate bill similar to the Stupak-Pitts amendment in the House version of the health bill, which prevents health plans that offer abortion services from receiving federal support. Many reproductive-rights groups criticized the amendment, saying it would restrict access to abortion in the United States. The Senate voted down Nelson's version of that amendment last week.

Nelson met with President Obama on Tuesday, and the president reportedly "spoke persuasively" to convince the senator to support the health bill, but the senator was not "won over."

The Wall Street Journal reports:

The abortion issue is likely to be among the most contentious in House-Senate negotiations on a final compromise bill. The House bill imposes strict limits intended to bar any federal funds from being used to pay for the procedure. The Senate bill, at least for now, would impose limits on coverage but still allow women who get government subsidies to enroll in a plan that covers abortion.

Nelson also said Thursday that he's concerned that the health care initiatives proposed in the bill aren't adequately funded.

"If you're going to extend coverage then obviously there has to be a way to raise the money. They way in which money is raised is not acceptable," he said. "So if there isn't a way to raise the money in tight times, I think you have to look at a scaled-back version."