Washington (CNN) – Senate Majority Leader Harry Reid, in conjunction with the White House, is working to see if the scaled back fiscal cliff package President Barack Obama laid out last week can get through Congress before December 31st.
Reid has made clear in private conversations he does not want to bring any bill to the Senate floor unless he is sure it will pass both the Democratic-led Senate and the Republican-held House.
His efforts were described to CNN by a senior Democratic source, who spoke on the condition of anonymity to describe private conversations and the behind-the-scenes process.
"It is to nobody's advantage to have a failed Senate vote at this point. This will be the last train we will have, and there is no sense in it leaving the station before we have assurance it will get through," the source said.
The reason for this is both political and practical.
Reid realizes that in all likelihood, he will need a number of GOP senators to cross party lines. He knows it is unlikely many Republicans would take the big political risk of voting for any tax increases if the vote turns out to be meaningless and the measure goes nowhere. Those Republicans will need to be able to tell their constituents their vote was to successfully avert the fiscal cliff.
The other reason is a failed vote in the Senate, followed by going over the cliff, may send an even worse signal to financial markets than simply going over the cliff.
It is still an open question, however, whether the vote threshold in the Senate would be a majority, or whether it would be 60 votes. That will depend on what Senate Republican Leader Mitch McConnell and Reid work out.
As far as the House goes, Democrats believe if they can get a bill through the Senate, it is likely they can get it through the House with most Democrats voting yes and, Democrats hope, about 30 or so House Republicans crossing party lines.
House Republicans leaders held a conference call Wednesday afternoon and made no decisions about when to bring their members back to Washington, according to a Republican source on the call. The leaders on the call simply "touched gloves," the source said.
House GOP leaders had promised to give members 48 hours notice before calling them back from their holidays at home.
Democratic sources have told CNN the most likely way to get a scaled-back package successfully through the Senate, House, and to the White House is to wait until the last minute – December 30 or 31.
Why? Several Democratic sources say they think it's likely that Republicans won't feel enough pressure until the bitter end.
The scaled back measure being developed by Democrats would first and foremost keep tax rates at current levels on incomes under $250,000 and let taxes go up on income above that threshold.
It would also extend unemployment insurance and likely extend the alternative minimum tax fix. Other things that may part of the measure include the Medicare "doc fix" and extending the current, lower estate tax rate, as well as other tax extenders.
– CNN White House Correspondent Brianna Keilar contributed to this report.