The Senate is expected to take a key vote Wednesday that would smooth the path for an eventual showdown over President Barack Obama's health care plan, but the midday vote is likely to inflame a raging war within the Republican Party.
A group of Republican senators tried to launch an old-fashioned filibuster Tuesday, despite pleas from party leadership to back off.
Sen. Ted Cruz, R-Texas, spent all night leading the effort -- and he and his allies continued talking Wednesday morning.
They've now engaged in the longest extended, nonstop debate in decades.
"I intend to speak in support of defunding Obamacare until I am no longer able to stand," said Cruz when he kicked off the debate Tuesday afternoon.
Behind him was an army of Senate allies and grass-roots conservatives, defying Senate Republican leader Mitch McConnell of Kentucky and other top Republicans who want to limit debate. They figure the Democratic-run Senate will never agree to strip the health care money.
Fight anyway, said conservative interest groups. "This is the ultimate betrayal," the Senate Conservatives Fund said of the Senate's top two Republicans, McConnell and John Cornyn of Texas. The Club for Growth said it would include the debate vote on its 2014 congressional scorecard.
The Senate is considering legislation that the Republican-led House of Representatives passed Friday. It would keep the government running through Dec. 15 while defunding Obamacare.
McConnell countered that the bill is what he and other Republicans want, so why delay? "We'd all be hard-pressed to explain why we were opposed to a bill we were in favor of," he said.
Cruz's backers argued that Democrats will put the funding back in eventually, a point reiterated by Senate Majority Leader Harry Reid, D-Nev. "I want to be very, very clear again: The Senate will not pass any bill that defunds or delays Obamacare," he said Tuesday after a meeting with Senate Democrats.
If some agreement on funding isn't reached by Oct. 1, when the new fiscal year begins, parts of the government will begin shutting down. Essential services and operations, such as national security, would continue.
Few on either side of the debate say they want a shutdown, aware that it's highly unpopular with the public.
"I just don't happen to think filibustering a bill that defunds Obamacare is the best route to defunding Obamacare," McConnell said. "All it does is shut down the government and keep Obamacare funded. And none of us want that."
But he's unable to quell an influential chunk of his caucus. Senate Republicans met privately Tuesday, and many urged Cruz to drop his delaying tactics. Cruz, a potential 2016 presidential contender, would not.
"I told my wife I now pick up the newspapers each day to learn what a scoundrel I am, and just what attack will come," he said. It's time, Cruz said, that lawmakers listen to their constituents, and they don't like the new health care law and feel increasingly alienated.
"We just had a six-week recess during August, where a substantial percentage of members of Congress chose not to hold town halls," Cruz said. "Not even to give constituents a chance to say their views."
Republicans pressured by the staunch conservatives are fighting back. Let vulnerable Democratic senators oppose defunding, they say, and then "the question ought to be why can't red state Democrats listen to their own constituents," Cornyn said.
McConnell, like many incumbent Republicans likely to vote to cut off debate, faces enormous pressure as he seeks re-election next year. Businessman Matt Bevin, who's challenging McConnell for the Republican Senate nomination in Kentucky, was quick to side with Cruz.
"There is really no difference between Mitch McConnell and Alison Grimes: Both would vote on the side of Harry Reid," Bevin said, referring to Democratic Senate candidate Grimes. "I am proud to support conservatives like Sen. Ted Cruz in his fight to defund Obamacare, and I promise the people of Kentucky: I will never cave to Harry Reid."
Wednesday's vote is likely to be the first in a series that could last for days. Sixty Senate votes are needed to limit debate, and supporters of a cutoff are expected to have far more than that.
Assuming they succeed, other procedural maneuvers might require more such votes later this week, and if the conservatives use all their weapons, a final vote on legislation is unlikely until Sunday. The measure, without the Obamacare defunding, is expected to pass.
It would then go to the House, where Speaker John Boehner, R-Ohio, would have to decide whether to allow a vote on that bill or try to change it so that it strips out the Obamacare money. Boehner hasn't said what he might do.
CORRECTION: An earlier version of this story wrongly said that the budget measure is expected to pass the Senate without the Obamacare "funding." It should have said "defunding."
By David Lightman
McClatchy Washington Bureau