Washington (CNN) Most everyone in Washington had three words after the Senate failed to pass any bill that would have resolved the status of millions of young undocumented immigrants on the verge of deportation:

"I don't know."

The question on everyone's mind was what comes next. But from lawmakers themselves to aides, as the dust settled on the failure of the Senate to advance a long-sought bipartisan compromise on the Deferred Action for Childhood Arrivals policy and border security, as well as a sharp defeat of a White House proposal, no one had any sense of what could protect the sympathetic population of immigrants who came to the US as children, sometimes called Dreamers.

President Donald Trump has opted to end DACA and, though the courts have put the termination on hold for now, thousands of them could begin to be vulnerable to deportation as soon as March if the court ruling were to be overturned.

"I don't know. I really don't know," Sen. Sherrod Brown, an Ohio Democrat, said as he left the Senate chamber Thursday afternoon, after a series of votes on different immigration proposals where none managed to reach the magic number of 60 to advance.

"I guess we're back to square two," said Sen. Johnny Isakson, a Georgia Republican. "We just finished square one."

The anticlimactic result of a long-anticipated Senate debate on immigration capped a week in which lawmakers mostly pointed fingers at one another to buy time for behind-the-scenes negotiations on a bipartisan compromise. The theory: Show President Donald Trump how much support a narrow DACA-border security bill could get and hope he'd get on board.

But the deal that ultimately did pick up eight Republican co-sponsors was brutally attacked by the White House and Trump administration agencies, who lobbied senators against it.

The bill failed 54-45, and the White House's proposal, which it lobbied hard for, picked up only 39 "yes" votes, even with three Democrats.

His promise to allow immigration to get to the floor fulfilled, Senate Majority Leader Mitch McConnell, R-Kentucky, then turned the chamber away from the issue Thursday evening, ahead of a planned weeklong recess next week.

"I don't see dedicated floor time (again)," Senate Majority Whip John Cornyn, R-Texas, told reporters. "What we'll have to do is keep talking and see if there's something other than what was rejected on the floor that people can agree to. ... I don't think it's going to be a path to citizenship, but we'll see."

Another shutdown?

There was already a brief government shutdown out of an effort to gain leverage for a DACA deal in January, but that threat had mostly been defused by the promise from McConnell to consider immigration this week.

Thursday, the first inklings of another standoff emerged.

"You may see something come up on the budget deal here, the omnibus," Isakson, referring to the spending bills Congress must write by March 23 to stave off yet another government shutdown.

Lawmakers were already putting pressure on Trump to find a way to get to yes, laying the blame for the failure to reach a deal at his feet.

"If the President wants to protect the Dreamers, he can do it. It's completely on his shoulders at this point," said Sen. Claire McCaskill, a Missouri Democrat. "He couldn't even get 40 votes (on his bill) and they control the chamber. So clearly the party is not following his lead."

Sen. Mike Rounds, the South Dakota Republican who's a co-author of the bipartisan bill that came up short of 60, said even before the vote that it was likely to fail -- but that he hoped getting more votes than the White House bill would start the ball rolling on a further compromise.

"Now let's start talking about how we can make improvements that the President would like," Rounds said. "Because we know it doesn't go anyplace unless the President says, 'I've fixed it, that I've had my opportunity to make it well, and that I can live with changes that work better for us.' "

Temporary fixes

Shortly after the bills failed, backup options started to emerge.

A trio of Republican senators introduced a bill that had all of the $25 billion the Trump administration wants for its border wall but extends DACA only in the form of continually renewable two-year work permits, far less than the pathway to citizenship for the immigrants that Democrats and moderate Republicans have called for, especially at that price.

Sen. Jeff Flake, an Arizona Republican, has a bill prepared that would be a temporary three-year extension of DACA with a smaller amount of border security, to at least stave off deportation until Congress can address the issue further.

But Democrats are likely to be unhappy with even that approach.

"I think that's a horrible outcome. We can't do that. We cannot do that," the Senate's No. 2 Democrat, Dick Durbin of Illinois, told reporters earlier this month. "The Dreamers have said, 'Do not do this to us or our families.' "

House course uncertain

In the House, a path forward is also murky.

Conservatives are heavily pressuring House Speaker Paul Ryan, R-Wisconsin, to call for a vote on a hardline measure that would go considerably farther than the White House proposal on immigration, with only temporary permits for the DACA population. The bill does not have enough Republican votes to pass, but conservatives have sent signals to Ryan that his leadership could be jeopardized if he doesn't appease their demands.

Without action from the Senate or concessions from conservatives, it's unlikely the House will turn to immigration on its own.

Asked what's next, one Democratic aide joked simply: "Armageddon?"