Senate Majority Leader Harry Reid (D-Nev.) won the battle Saturday night, but he’s far from winning the war within his own caucus over health care reform.

Having practically moved heaven and earth to persuade all 60 members of the Senate Democratic Conference to support the notion of even having a health care debate, Reid now faces the thorny task of finding a way to get his $848 billion measure passed before Christmas.

“We can see the finish line, but we’re not there,— Reid said following the 60-39 vote to bring the bill to the floor on Saturday night. “The road is a long stretch. … We have the momentum to keep this process moving, I have no doubt about that.—

Reid added that he is mindful that not all Democrats agree on the underlying substance of the bill, including over whether it should include a public insurance option to compete with private insurers. “We’ve got some things to work out, but we’re going to get a bill,— he said.

Given the statements of wayward centrist Democrats, however, Reid may be understating what lies before him.

The Majority Leader needed 60 votes on Saturday to kill a Republican filibuster of the motion to proceed to the health care measure. If successful, the filibuster would have prevented the bill from being debated or amended on the Senate floor. Reid will face that same 60-vote threshold when he attempts to call a final vote on the bill.

In announcing their support last week to start the debate, moderate Sens. Mary Landrieu (D-La.), Blanche Lincoln (D-Ark.) and Ben Nelson (D-Neb.) warned they cannot be counted on to support the package as it stands. All three oppose the measure’s creation of a public option that states may opt out of, among other issues, and have indicated they may block future progress on the bill if the public option is not removed. Sen. Joe Lieberman (ID-Conn.) has also threatened to filibuster the measure over the public option.

Given that he appears to be four votes shy of the 60 needed to break another filibuster of the bill, Reid indicated Saturday night that a compromise might be needed, saying Landrieu plans to work with Sens. Charles Schumer (D-N.Y.) and Tom Carper (D-Del.) on a “public option that’s acceptable to all Democrats.—

Landrieu said Saturday that she believes Democratic leaders are aware of the challenge they face in the coming weeks.

“I would say that I believe it’s going to be very clear at some point very soon that there are not 60 votes for the current [public option] provision in the bill and that the leader and the leadership are going to have to make a decision, and I trust that they are going to figure out how to do that,— Landrieu said.

Indeed, in the floor speech Lincoln gave announcing her support for the vote, she threatened to filibuster the final bill if it includes a public option.

“I’ve already alerted the leader, and I’m promising my colleagues that I’m prepared to vote against moving to the next stage of consideration as long as a government-run public option is included,— said Lincoln, who faces a potentially difficult re-election next year.

Those types of statements from centrists have not been sitting well with liberals, however, who have said they might not vote for a bill if it doesn’t have a public option. They say they’ve compromised enough already.

“I think, in the end, I don’t want four Democratic Senators dictating to the other 56 of us and to the country, when the public option has this much support, that it’s not going to be in it,— Sen. Sherrod Brown (D-Ohio) said Sunday on CNN. “I don’t think they want to be on the wrong side of history. I don’t think they want to go back and say, you know, on a procedural vote, I killed the most important bill in my political career. I don’t think they want to be there on that. So I think, in the end, we get them.—

Landrieu, Lincoln and Nelson have been working with Sen. Olympia Snowe (Maine), who opposed Democrats on Saturday but was the only Republican to vote for the Senate Finance Committee bill in October. Snowe supports a plan to allow a public option to be “triggered— if private insurers cannot reduce costs on their own. If Reid decides to accept that proposal as a compromise, however, he could lose Lieberman’s vote because the self-described Independent Democrat has said he would oppose a public option in any form.

Snowe said last week that she is still in talks with moderates such as Carper as well as with Reid and the White House, but she has not finalized any language because the Majority Leader has made it nearly impossible for any of her proposed compromises to prevail on the Senate floor.

In explaining why she was supporting her party’s attempted Saturday night filibuster, Snowe said: “I don’t have 60 votes to change any critical issues and fundamental issues, such as the opt-out provision, so I don’t want to … vote to unleash that force. It’s sort of giving tacit agreement that I could accept that so I have to make a statement in the best way I know how.—

But Republican leaders are hoping to keep up the pressure on Democratic centrists and Snowe to kill the bill before a final vote — particularly considering that with only 40 Members in their Conference they do not have enough votes to sustain a filibuster on their own.

“All it takes is one vote, just one,— Minority Leader Mitch McConnell (R-Ky.) said on the floor Saturday night. “The simple math is this: If there were one Democrat, just one of our friends on the other side of the aisle, just one who would say no tonight, none of this would happen.—

Reid has repeatedly rejected using budget reconciliation rules to pass a health care measure despite the fact that it would prevent a filibuster and require only a 51-vote majority for passage. However, reconciliation rules also strictly limit what can be included in a bill, and Republicans could use the rules to force votes on dozens of politically difficult amendments.

Senate Majority Whip Dick Durbin (D-Ill.) said last week that Reid is committed to finding a 60-vote solution to the health care issue and that he would continue to tweak the bill to address Democrats’ concerns.

“Harry said yesterday we’re working on a 60-vote margin, and what he’s going to do after the Thanksgiving recess, probably during as well, is talk to the individual Senators, make sure they each have some peace of mind about what the bill does,— Durbin said Friday.

But Durbin acknowledged that Republicans could attempt to wreak havoc on the Democratic plan to allow their own Members to alter the bill to their satisfaction through the amendment process, because consent is needed to schedule votes on amendments.

“I think that the endgame for us is a reasonable effort at debate on amendments, certainly to allow the Republicans, if they come up with a health care reform bill, to offer it and to debate some of the major amendments— Durbin said. “And then we hope to build our consensus in our caucus. That will mean changing some of the provisions in the current bill, I’m sure, before we get to final passage.—

He added that Republican delay tactics and refusals to allow votes on amendments would not work, saying it was unlikely Reid would sit by and allow that to happen.

“There comes a point when the Senate has to decide,— Durbin said. “If we feel that we have a good bill with 60 votes and 60 Senators, we’ll say, ‘All right, we’ve given fair opportunity to Republicans to offer amendments. … They will offer amendments until they feel they’ve beaten us down and nothing passes. We can’t let that happen.—

Even if Reid prevails and passes a bill this year, even more hurdles lie ahead.

Challenging conference negotiations loom with the House, which approved a more liberal health care plan earlier this month. Speaker Nancy Pelosi (D-Calif.) made clear last week she prefers the Senate bill on one point: It takes a friendlier approach to abortion rights. But the issue remains explosive within her own Caucus, and it is not clear whether House Democratic leaders will be able to walk back the hard-line restrictions to the procedure they accepted to win over a clutch of Democratic abortion-rights opponents.

On several other major provisions, Pelosi is likely to drive a tough bargain. A majority of House Democrats is on record strongly opposing a key piece of the financing mechanism for the Senate bill: a tax on expensive health insurance plans. The House plan imposes a “millionaire’s tax— to help cover its $1.2 trillion price tag. The Speaker last week also signaled that she will fight to preserve a House provision that allows illegal immigrants the ability to use their own money to purchase health insurance through a new exchange — something the Senate bill forbids. And then there’s the public insurance option, which faces a difficult, if not impossible, path in the Senate but that Pelosi and a broad swath of her liberal ranks have staked out as a must-have measure to impose accountability on the insurance industry.

Tory Newmyer contributed to this report.