Republicans are trying to win Democratic votes on the stopgap measure Tuesday by attaching a two-year extension of funding for Community Health Clinics and other provisions.
Even if House GOP leaders are able to muscle their bill to passage without Democratic votes, as seems likely thanks to backing from the conservative House Freedom Caucus, the outcome in the Senate is uncertain. The narrow 51-seat Senate Republican majority must rely on Democratic support to reach the 60-vote threshold for passage.
"Unfortunately, we are back at that point that we were just a few weeks ago," said House Majority Leader Kevin McCarthy, R-Calif. "Last time, we had to have a shutdown. Hopefully we will not be in that situation again."
Negotiators have been trying to craft a more lasting budget accord to fund the government through the remainder of the fiscal year, which ends Sept. 30. They want to boost all spending beyond the strict caps imposed under a 2011 budget deal.
If a broader budget agreement is struck, the Senate could swap it in for the House's stopgap measure, with a fresh round of voting before Thursday's midnight deadline to fund the government.
But mounting deficits are beginning to worry lawmakers after passage of the massive $1.5 trillion tax cut package, especially as they pile on disaster aid for states hit during the especially devastating hurricane and wildfire season. The volatile stock market has only amplified lawmakers' concerns.
"At some point the market's going to wake up to the fact that you're going to start running $1 trillion deficits all over again," said Rep. Mark Sanford, R-S.C., the state's former governor, who worries that the stopgap measures are viewed as "a real sign that Washington doesn't work, that it is dysfunctional at some level."
The immigration debate involves efforts to craft a bill to protect young immigrant "Dreamers" from deportation after Trump formally ends the Obama-era Deferred Action for Childhood Arrivals program.
Democrats shut down the government for three days last month as they pushed the immigration issue to the forefront of the agenda, then relented after winning a promise from Senate leaders that it would be the next debate. Groups of lawmakers are meeting behind closed doors to develop legislation that would also include border security enhancements and other immigration law changes.
As senators struggle to craft a bipartisan immigration bill, some are mulling a one-year extension to DACA, which allows immigrants who came to the country illegally as minors to apply to live and work here as adults. Under Trump's order, the program was to have expired March 5, but a court case has allowed it to keep running for now.