U.S. Congressional Republicans, already facing a difficult election landscape, confronted a prospect Sunday they had worked feverishly to avoid: a threat by President Donald Trump to shut down the government over funding for a border wall.

“I would be willing to ‘shut down’ government if the Democrats do not give us the votes for Border Security, which includes the Wall!” Trump wrote on Twitter. “Must get rid of Lottery, Catch & Release etc. and finally go to system of Immigration based on MERIT! We need great people coming into our Country!”

Last week, Republican leaders thought they had reached a deal with Trump to delay a confrontation on funding for the wall until after the November midterm elections, according to a person familiar with their discussion.

But Trump’s shutdown threat, in which he also demanded several pieces of a comprehensive immigration overhaul that is stalled in Congress, has opened the door to a politically bruising spending fight as the fiscal year ends in September.

With the election coming just weeks later, the party can ill afford a disruption that voters — already disgusted by Washington dysfunction — may hold the president accountable for.

A shutdown would also distract from Senate Republicans’ main business in September: their push to confirm Judge Brett M. Kavanaugh to the Supreme Court.

“We’re going to have a challenging midterm anyway, and I don’t see how putting the attention on shutting down the government when you control the government is going to help you,” Representative Tom Cole, Republican of Oklahoma, said in an interview.

Representative Steve Stivers of Ohio, the chairman of the committee charged with electing Republicans to the House, insisted that a shutdown was unlikely.

“I don’t think we’re going to shut down the government,” Stivers said on the ABC News program “This Week.” “You know, I think we’re going to make sure we keep the government open, but we’re going to get better policies on immigration.”

Democrats and Republicans have in fact made unusual progress on the 12 appropriations measures necessary to keep the government operating. Current funding for the government expires Sept. 30.

Trump’s shutdown threat Sunday was part of a flurry of tweets in which he attacked favorite targets like the “Robert Mueller Rigged Witch Hunt” (“an illegal Scam!”) and the news media (“driven insane by their Trump Derangement Syndrome.”) (SD-Agencies)