For their part, top Senate Republicans said they doubted there was enough time for the chamber to deal with the $205 billion package, which includes a patch to stop the alternative minimum tax from hitting middle-class taxpayers and also extends incentives for renewable energy and research.
Senate Minority Whip Jon Kyl (R-Ariz.) also stood in the way of Reid's attempt to move the extenders package forward by unanimous consent on Wednesday evening.
The two also said the work on the tax breaks would serve as good practice as Congress gears up for a comprehensive overhaul of the entire tax code, possibly next year.
The Senate is currently trying to pass a stopgap spending bill to fund the government for six months after Oct. 1.
And Kyl (R-Ariz.) also suggested to reporters on Wednesday afternoon that lawmakers would want to seek changes to the extenders package, which five Republicans — including Kyl — opposed when the Finance Committee passed it in August.
“You have to go through the whole process, and I suspect that’s one of those things that’s complicated enough that a lot of members have things that they’d like to do in terms of offering amendments and so on,” Kyl said. “So I think it’s very, very difficult for the leader to get it up.”
Even on the off chance the Senate does deal with tax extenders soon, the issue is almost certain to spill over into the post-election session of Congress.
The tax-writing House Ways and Means Committee has been conducting its own review of the expired and expiring tax breaks, and top Republicans on the panel have been saying for months they planned to deal with extenders in that lame-duck session.
Lawmakers will also have to deal with larger issues after the election, including sequestration and the expiring Bush-era tax rates, meaning extenders could easily be wrapped up in the broader fiscal debate.
Still, some Senate Democrats said they were hopeful more substantive work on extenders could be completed in the next few days, and that Reid and Minority Leader Mitch McConnellMitch McConnellDisconnect: Trump, GOP not on same page GOP senator: There will never be full U.S.-Mexico border wall Overnight Tech: Dem wants to see FCC chief's net neutrality plans | New agency panel on telecom diversity | Trump calls NASA astronaut MORE (R-Ky.) will continue to discuss the issue.
Majority Whip Dick DurbinDick DurbinTop Trump officials push border wall as government shutdown looms Top Dem: Shutdown over border wall would be 'height of irresponsibility' Sunday shows preview: Trump stares down 100-day mark MORE (D-Ill.) added that the effort on tax extenders is separate from the continuing resolution debate.
“Harry is waiting to hear from Mitch McConnell as to whether there will be an effort outside the CR to do that,” he said. "Currently, Harry is trying to take a separate path."
But a Senate Republican staffer laughed at the idea that substantive negotiations were going on over extenders, and another GOP aide said a "list" of open items is being looked at because the Senate could be in session through Sunday.
The second aide, however, doubted that the tax extenders bill will make the cut, and even Baucus sounded less than optimistic on Wednesday.
"I'd like to, but there are not a lot of days left," he told The Hill.
— This story was updated at 5:01 p.m. and on September 20, 2012 at 7:45 a.m.