Even though he doesn’t yet have an official cost estimate or promises of a filibuster-proof vote, Senate Majority Leader Harry Reid (D-Nev.) is confident he’ll be able to kick off debate on a massive health care reform measure before Thanksgiving.

Reid wanted to get the ball rolling on the overhaul early this week armed with a Congressional Budget Office analysis, but because that CBO score didn’t come on Friday as he had hoped, Democratic aides said the Majority Leader is prepared to push back his timeline. Reid may keep the Senate in session into the week of Thanksgiving in order to overcome one of the biggest hurdles facing the bill: producing the 60 votes needed to beat back a GOP filibuster that would prevent the bill from even being considered on the Senate floor.

Though a few moderate Democratic Senators such as Ben Nelson (Neb.), Mary Landrieu (La.) and Blanche Lincoln (Ark.) have yet to commit to supporting the start of the health care debate, Democratic aides said last week that they do not believe that any member of the 60-strong Democratic Conference will vote to prevent the full Senate from bringing the measure to the floor.

“We understand that there are people who have concerns about this bill. They’ll be able to address those concerns on the Senate floor, but the first step is starting debate,— one Senate Democratic leadership aide said. “While Senate Republicans might be OK with robbing the American people of that opportunity, we are confident Senate Democrats are not.—

Another senior Senate Democratic aide said fence-sitting Democrats just need something to point to before committing to vote down a filibuster of the motion to proceed. Reid cannot produce legislative language until he has the CBO score in hand, perhaps by Tuesday or Wednesday.

“Just eliminating the mystery of what’s in the bill will be enough to get these moderates to ‘yes’ on the motion to proceed,— the aide said.

The key vote, which Reid plans to call after he receives the CBO score, would be on a motion to limit debate — or invoke cloture — on a motion to proceed to the bill. The leadership aide said Reid is working under the presumption that he will have a CBO score “sooner rather than later— this week and that the Senate will be in a position to kick off debate before Members go home for Thanksgiving.

Reid wants to get the cloture vote on the motion to proceed over with before the holiday because he would like to spend all three weeks before Christmas amending and debating the health care bill. If he has to wait until after Thanksgiving to take the vote, the time-consuming procedural hoops he has to jump through could delay the start of the amendment process until the second week of December.

Because of the additional time the CBO needs to score the bill, it remains unclear whether Reid will heed the call of centrists such as Lincoln to wait 72 hours after the CBO score is unveiled to have a vote.

“Members will have time to digest this bill,— said the leadership aide, who declined to say whether that meant there would be a three-day review period.

But whether to wait 72 hours is just one of Reid’s concerns as he seeks to cement Democratic votes to kill the filibuster over the next few days.

The flap in the House over whether any new federal health insurance programs would fund abortions has now spilled over into the Senate, with the handful of anti-abortion-rights Democrats calling for language that would prevent private insurers from covering the procedure for women receiving federal subsidies and abortion-rights supporters threatening to oppose the bill if that House-passed provision is included.

Senate aides indicated that Democratic leaders have not yet decided how to address the issue. The bill that passed the Senate Finance Committee included a ban on federal funds being used for abortions but did not go so far as to prohibit private insurers from offering a benefit to subsidized women.

The leadership aide said that decision would be a topic of discussion for Senators this week as Reid, who opposes abortion rights, looks for consensus on whether to put stronger abortion language in the bill or allow Senators to fight it out on the floor.

But the issue still could be a threat to Reid’s plan to bring up the bill this week. Nelson has said he may vote to filibuster the motion to proceed: “If it isn’t clear that government money is not to be used to fund abortions, I won’t vote for it.—

Reid has also been exploring other options for paying for the bill and keeping the total price tag under $900 billion, as President Barack Obama has called for. Unions have balked at the Finance bill’s plan to tax high-cost, or “Cadillac,— health care plans, and liberals are concerned that the measure does not offer sufficient subsidies to middle-income Americans who may not be able to afford insurance under the bill’s individual mandate.

“All parties knew that we were going to have to strengthen the piece of legislation that came out of Finance,— the leadership aide said. “We need to keep our options open on available funding sources as we continue to put forth the strongest bill possible that is affordable for middle-class Americans.—

The aide confirmed an Associated Press report that Reid has considered increasing payroll taxes on individuals with incomes over $250,000 a year but said no decisions have been made.

Even with the tweaks Reid is seeking to satisfy various constituencies in the Democratic caucus, the outcome on the floor is far from certain. Sen. Joe Lieberman (ID-Conn.), who caucuses with Democrats, has said he will vote to bring up the bill while repeatedly threatening to filibuster to close off debate if the measure still includes a public insurance option. Reid has said the bill he plans to bring to the floor would contain a public option with an opt-out provision for the states. Other centrists such as Nelson have similar concerns about the public option but have not said whether they would filibuster the measure over it.

Even so, the leadership aide cautioned that Senators who have seemingly drawn lines in the sand over one issue or another may see things differently after three or four weeks of debate.

“This is all academic until you start having votes on the floor,— the aide said.