Lawmakers and the White House must agree on something to avert a shutdown at 12:01 a.m. Saturday, when the existing stopgap spending measure expires. The ball appears to be in House Republicans’ court, as that conference’s members haggle over whether to send something to the Senate that would last through Dec. 22 or closer to New Year’s Eve.

The White House has not taken a position on the length of the coming continuing resolution. After the president initially signaled a willingness to consider addressing the Obama administration’s DACA immigration program as part of the spending measure, Trump and his top aides in recent weeks walked back that position. Republican lawmakers have followed suit, but at least a handful of Democratic votes will be necessary in the Senate, giving that party ample leverage in the spending negotiations.

A key Democrat immediately slammed Trump’s threat.

“The president’s continuing threats to shut down the government, and Republican leadership’s game-playing on the course forward, raise serious doubts about whether they are engaging in a good faith effort to develop a responsible funding package,” said Matt Dennis, spokesman for Rep. Nita M. Lowey of New York, the House Appropriations Committee’s top Democrat.

Trump is slated to huddle Thursday at the White House with Speaker Paul D. Ryan, Senate Majority Leader Mitch McConnell, House Minority Leader Nancy Pelosi and Senate Minority Leader Charles E. Schumer about averting a shutdown. Those five had a meeting on the books last week, but Trump, with a single tweet blasting Pelosi and Schumer, set in motion dominoes that led to the Democratic leaders skipping the session.