The president has spent his first months in office freezing out Democrats, who have in turn opposed him routinely. Now they need each other to keep the government open.
Top Democrats are demanding concessions on health care in exchange for their support on a bill to fund the government. Mr. Trump called the demands “unserious.”
After House Republicans pushed through a measure to avert a shutdown, Democrats blocked it in the Senate, demanding more than $1 trillion for health programs.
Senator John Thune, the majority leader, said he would call up the Republican proposal for another vote when senators return to Washington on Sept. 29, after a week spent working in their home districts.
After rejecting a G.O.P.-written plan to keep federal funding flowing, Democrats released a counteroffer that would add more than $1 trillion in health spending.
“The contrast between the Republican proposal and what Democrats have put forward is glaring,” said Senator Chuck Schumer of New York, the Democratic leader.
The speaker put forward a stopgap bill to fund the government past Sept. 30, saying there was “zero chance” he would add concessions Democrats have demanded.
Republicans are signaling a new openness to extending health subsidies as Democrats suggest they want health care concessions to keep the government open.
On national security, spending and oversight, the president continues to undercut the legislative branch, and Republicans in charge have done little to stop him.