Late Monday night, as the clock ticked toward the first government shutdown in 17 years, the Senate tossed aside another House budget proposal.

It was the third attempt to pass a government funding bill before a midnight deadline, but it also included a one-year delay of the Obamacare mandate that everyone buy insurance and eliminated a health care subsidy for members of Congress and their staffs -- the latest Republican effort doomed as a legislative non-starter.

The Democratic Senate quickly rejected the offer, with Senate Majority Leader Harry Reid, D-Nev., complaining that he would not “be bullied” by the House into renegotiating Obamacare.

A short time later, in a basement hallway of the Capitol, a House Republican aide sighed into his cell phone. “We’re back to square one.”

Congress needed only to approve a routine funding bill to prevent a government shutdown. President Obama declared that it was the “responsibility” of Congress to do so. Instead, Republicans seized the opportunity to rev up their fight to eliminate or weaken the Affordable Care Act.

The showdown will perhaps be a defining moment for House Speaker John Boehner, whose credibility inside and outside his caucus will hinge on the outcome of the high-stakes legislative scuffle.

It wasn’t even Boehner’s fight to choose.

The movement might have fizzled early, but for the galvanizing effects of goading by outside groups such as the Heritage Action, and the spotlight-stealing performance of Sen. Ted Cruz, R-Texas, who shot to the forefront with a dramatic 21-hour, vote-delaying speech on the Senate floor.

Cruz’s influence, in particular, has been polarizing among Republicans. For House leaders looking to avert a shutdown, he was infuriating, undercutting their odds of approving a realistic budget. For some conservatives, though, including a group of House members with whom Cruz plotted strategy, Cruz was a timely mascot.

Sen. Mike Lee, R-Utah, worked with Cruz to pressure Republicans to back the Obamacare fight even if it meant a government shutdown. Both were unfazed by the fusillade of criticism from within their own party.

“We’re not going to agree to stand down on an issue as important as this one simply because some of our Republican colleagues don’t feel the same way we do,” Lee told the Washington Examiner.

Lee and Cruz alone could not steamroll a Democratic Senate majority, however. They needed the House to sustain the fight.

And it did, even as the Senate rejected every proposal Republicans sent over, the budget deadline passed and the government shut down.

Back to square one and out of ideas, House Republicans decided to call on the Senate to join a bipartisan conference committee to iron out chasmic differences over the bill. The House Rules Committee met at the 11th hour, literally, to review the latest bill, and emotions boiled over.

“At this point there is no way to avoid a shutdown, and that's on your shoulders,” said Rep. Jim McGovern, D-Mass., pointing at his Republican colleagues.

Rep. Alcee Hastings, D-Fla., was even more blunt.

“You all have just lost it,” he said.

The rancor wasn’t just for show. Lawmakers were in an ideological stalemate.

The House once again approved its proposal knowing it would die in the Senate shortly after daybreak.

“The House has made its position known very clearly,” Boehner told reporters. “We believe that we should fund the government, and we believe there ought to be basic fairness for all Americans under Obamacare.”

There would be no fifth proposal, no re-imagined Plan B. With the shutdown settling over Washington on Tuesday, House Republicans were digging in, hoping to approve a few small temporary spending measures that collectively would keep the government open but not fund Obamacare.

House Republicans gathered for a photo-op at a half-empty conference table, pretending to await Senate negotiators who weren't coming. At a meeting a short time later, House Majority Leader Eric Cantor tried to rally the rank and file to continue the effort.

“We are in this fight,” Cantor said.

But, after the meeting, Rep. Scott Rigell looked tired. He had supported his party's efforts to derail Obamacare, but he was now one of a few House Republicans ready to call a truce.

“I’m proud of the fight, and I think we did everything we could,” Rigell, R-Va., said. “I think the question is, if you look at what we’re fighting for now ... is that objective worth disruption to our economy and to our military?”

His answer was no. “That doesn’t advance our conservative cause,” he said.