The Senate just voted by a 60-34 margin to advance a $447 billion spending bill by invoking cloture, and a vote on final passage is expected tomorrow.

The chamber will remain in session today and tomorrow and will be debating the spending bill and health care, but it’s unlikely that there will be votes on any health care amendments this weekend, a Senate Republican aide tells me.

Meanwhile, the Hill reports of growing doubts among Senate Democrats that they will pass a health care bill by Christmas, because at this point virtually everything will have to go perfectly for them. One big factor is how long it will take for the Congressional Budget Office to get back to them with an estimate on the new Medicare expansion idea being touted by Senate Majority Leader Harry Reid as a “compromise.” 

To pass a bill before Christmas, Reid would have to get a good CBO score early next week, get all 60 Democrats on board, give 72 hours before voting to advance the final bill, clear three 60-vote procedural hurdles that would have to be spread out over six or seven days, and then hold the final vote.

Yet 10 Democrats have already sent a letter to Reid expressing concerns about the Medicare expansion idea, and the liberal Sen. Bill Nelson of Florida has called it a “non starter.”

A Senate Republican aide also tells me that they’ll need to vote on a defense appropriations bill by next Friday, and it’s still unclear whether Democrats will try to attach legislation to raise the federal debt limit to it.