The U.S. government was bracing on Monday for its first shutdown in nearly two decades, with frustrated and weary lawmakers gathering at the U.S. Capitol but harboring little hope of finding a compromise that would keep the government operating past midnight.

Senate Majority Leader Harry M. Reid (D-Nev.) has vowed to reject a funding bill approved by the House early Sunday because it would delay Obama’s signature 2010 health-care law for one year and repeal a tax on medical devices.

Reid will move to table the House amendments when senators convene early Monday afternoon. That exercise requires a simple majority and can be accomplished solely with Democratic votes. [Click here for live updates on the shutdown crisis.] By midafternoon, House GOP leaders are likely to face a decision again about how to handle the simple, six-week government funding bill that the Senate approved last week.