ABC News’ Matthew Jaffe reports: With the tax bill passed through the Senate and headed to the House, senators are now set to begin work on ratifying the START treaty and passing the omnibus spending bill to fund the government for the next year. Debate on the former officially starts Thursday morning. It needs 67 votes for ratification. As for the latter, Senate Majority Leader Harry Reid is expected to bring the spending bill to the chamber’s floor as well, part of the Democrats' plan to dual-track both bills in an effort to speed up the Senate's pace with so little time left in the lame-duck. Democrats lose much of their majority when the new Congress is sworn in early in January – and control of the House switches over to Republican hands. Time is important on the funding front for another, more important reason: the latest stop-gap temporary funding resolution runs out Sunday at 12:01am. If Congress does not act before then, then a government shutdown could occur. Senators expect to spend the next few days working on these two issues, with the Senate now planning to stay in session all weekend. Reid said Wednesday he hopes the Senate can wrap up all its work – START and funding, plus consider the Don't Ask Don't Tell repeal passed thru the House, plus the DREAM Act, the 9/11 bill, and a slew of nominations – around next Monday or Tuesday. But that's not going to be easy, not with Republicans in no mood to cooperate. (see DeMint, Jim) GOP senators have a beef with so little time to debate and amend the nuclear disarmament treaty (Kyl, Alexander, etc.), the earmarks in the massive omnibus (McCain, Thune, Cornyn, etc.), the DADT repeal itself (McCain, etc.), and so on and so on. The fact that Reid and Kyl are now fighting about the importance of Christmas pretty much says it all.