Congress returns to Washington Tuesday with a government shutdown less than five days away and lawmakers are still scrambling for ways to avoid it.

That wasn't supposed to be the case.

It has been less than three months since House Speaker Kevin McCarthy, R-Calif., reached an agreement with President Biden that set spending levels for the year. That agreement was part of a bipartisan debt limit package that overwhelmingly passed the House in a 343-117 vote.

McCarthy negotiated that plan. House Democrats agreed. So did Senate Republicans. And Senate Democrats. But a small group of hard-line conservatives in the House immediately rejected the plan for failing to agree to deeper spending cuts. The group pressured McCarthy into backing away from the agreement.

Details of a possible Senate-led spending stopgap began to emerge Monday night as Senate leaders worked on a bill. Any Senate-led solution would require unanimous agreement to move fast enough to avoid a shutdown, and even then, a deal would almost certainly require votes from House Democrats in order to pass.

For the past several months, McCarthy has accepted the conservative demands as he attempts to navigate a razor-thin majority of just four votes.

McCarthy has said, repeatedly, that he does not want to see the government shut down.

"I don't think anybody wins a shutdown," McCarthy told reporters in the Capitol last week. "Think for one moment what a shutdown does. It stops paying our troops. How do you have more leverage in that situation? I've watched shutdown after shutdown, everybody loses."

House Republicans spent the weekend setting up a plan to hold votes on several of the 12 annual funding bills that include deep spending cuts. Those bills align with conservative demands, but they will not prevent a shutdown.

Senate takes spending steps

Senate Majority Leader Chuck Schumer, D-N.Y., has been working with Republican counterparts on their own solution, though the fate of a bill is far from certain.

Last week, Schumer moved a legislative vehicle forward that could be used as a stopgap spending bill and sent to the Republican-led House. The Senate could take a procedural vote to start floor work on the plan Tuesday evening when they return from their holiday recess.

"As I have said for months, we must work in a bipartisan fashion to keep our government open, avoid a shutdown and avoid inflicting unnecessary pain on the American people. This action will give the Senate the option to do just that," Schumer said.

However, the process could take days even with the objection of one member of the Senate.

It's unclear if the Senate could muster enough bipartisan support for the plan if it includes additional aid for Ukraine or several, recent U.S. public disasters, including the deadly fires in Maui, a key objective for Democrats.

House could still block a stopgap spending bill

Even if the Senate is able to move quickly on a stopgap, it's unclear if McCarthy would allow a Senate plan to get a vote. Florida GOP Rep. Matt Gaetz has threatened to begin the formal process to remove McCarthy as speaker if he does not comply with far-right demands.

McCarthy is also under pressure from former President Trump, who has pushed for spending cuts. Trump is in close contact with some of the GOP holdouts in the House and has posted publicly in favor of cuts.

"The Republicans lost big on Debt Ceiling, got NOTHING, and now are worried that they will be BLAMED for the Budget Shutdown. Wrong!!! Whoever is President will be blamed, in this case, Crooked (as Hell!) Joe Biden!" Trump posted Sunday on his social media site Truth Social.

Trump went on to criticize Senate Minority Leader Mitch McConnell, R-Ky., who has been supportive of a stopgap spending bill and has said he supports the agreement McCarthy reached with Biden during the debt limit talks.

A small bipartisan group of lawmakers known as the Problem Solvers Caucus has begun work on a plan to use a House procedure known as a discharge petition to get around McCarthy and force a vote on spending. That plan could take weeks and would require at least 218 votes, meaning Democrats and Republicans would have to agree to the strategy.

For now, that leaves the fate of government spending largely in McCarthy's hands.