If lawmakers can't reach a deal by midnight, parts of the government will shut down.
So what happens after that? Should the government shut down, most lawmakers who have spoken to CNN say they plan to go home for the holidays. They'll just be prepared to come back if any kind of compromise is reached.
But, that's problematic.
First, that they don’t see a quick resolution to this fight. President Trump has dug in. And the bill doesn't have majority support in the Senate.
Also, things often get resolved because lawmakers are bored and tired of staying in town. That ultimately helps lead to a compromises during impasses.