The Senate was headed on Friday toward a critical vote to avert a government shutdown at midnight, after Senator Chuck Schumer of New York, the Democratic leader, said he would join Republicans in pushing it past any filibuster by his own party.
A vote to move forward with the G.O.P.-written measure, which would fund the government through Sept. 30, was expected early Friday afternoon. Republicans would need eight Democrats to join them in voting to allow the bill to advance, and Mr. Schumer privately indicated to Democrats on Thursday that he had lined up the votes.
If the Senate fail to pass the funding extension, federal funding would lapse at 12:01 a.m. on Saturday.
Mr. Schumer’s abrupt decision to reverse himself and allow the spending legislation to advance stunned many of his colleagues and angered many Democratic lawmakers and progressive activists. Many in his party have vociferously opposed the temporary spending measure, arguing that it was a capitulation to President Trump, and have said that they would rather shut the government down than vote for it.
As recently as Wednesday, Mr. Schumer was arguing strongly against the bill, instead proposing a monthlong alternative to allow Congress to reach an agreement on individual spending measures with specific instructions over how federal funding should be doled out.
But he reversed course on Thursday, with a shutdown looming and amid concerns that Democrats would be blamed. He argued that a shutdown would only play into the hands of Mr. Trump and Elon Musk, ceding more power to them as they move to defund and dismantle whole swaths of the federal government. In that scenario, he said, the Trump administration could decide which federal workers would be “nonessential” and furloughed. And he warned that Republicans would have little incentive to reopen the government once it shut down.
“As bad as the C.R. is,” Mr. Schumer said on Friday morning, referring to the bill known as a continuing resolution, “I believe that allowing President Trump to take more power is a far worse option.”
It is unclear how many Democrats might join Mr. Schumer in voting for the measure, or who might do so. Other than Mr. Schumer, only one Democrat, Senator John Fetterman of Pennsylvania, has publicly supported the bill.
A number of centrist Democrats, as well as Democrats facing tough re-election contests next year, who had been as potential supporters of the measure, have said they would oppose it. Senator Jon Ossoff of Georgia, who will face voters next year, said in a statement that he would vote to block the legislation in part because it failed “to impose any constraints on the reckless and out-of-control Trump administration.”
“Both parties in Congress must fulfill our constitutional obligation to check the president,” Mr. Ossoff said.
At issue for Democrats is that the stopgap measure does not contain the specific congressional instructions to allocate money for programs usually included in spending bills. Democrats Senator Patty Murray of Washington, the party’s lead appropriator, have warned that the lack of explicit directions would essentially create slush funds for the Trump administration at a time when they have already disregarded spending directives set by Congress.
“We have already seen how far President Trump, Elon Musk and Russ Vought are willing to twist — and outright break — our laws to suit their will,” Ms. Murray said. “But House Republicans are setting them up to make everything so far look like child’s play.”
