Key Republican senators head to the White House Thursday afternoon to meet with President Donald Trump, hoping to resolve a border brawl that could hold up a year-end spending package and lead to a partial government shutdown.

The White House session could make clear whether Trump is prepared to give any ground in his request for a $5 billion down payment on a southern border wall — or whether he’s prepared to trigger a shutdown if he doesn’t get his way. Senate appropriators have offered only $1.6 billion in their bipartisan version of a Homeland Security spending bill.

“I think what we might figure out is what’s doable, what can we do to move the process, what can we do to satisfy him enough to move the process,” said Senate Appropriations Chairman Richard C. Shelby, R-Ala, who plans to attend the meeting with Senate Majority Leader Mitch McConnell, R-Ky. “The meeting with the president, I would think, the impetus would be how do we resolve the wall.”

Democratic leaders, who aides said won’t attend, have shown no signs of bending toward Trump’s request, particularly after winning a House majority and largely holding their own in the Senate after bruising midterm elections.

“The Democrats and Republicans came to a $1.6 billion agreement,” Senate Minority Leader Charles E. Schumer, D-N.Y., told reporters Wednesday. “We believe Democrats and Republicans should stick with their agreement and not let President Trump interfere. Every time he interferes, it gets bollixed up.”

Congressional leaders hope to pass a funding package that would wrap up the seven unfinished spending bills for fiscal 2019, which began Oct. 1, before a stopgap measure runs out on Dec. 7. The package could encompass nearly $313 billion in discretionary spending subject to budget caps, including the Homeland Security bill that contains border wall money.

Four of the outstanding measures — Agriculture, Interior-Environment, Financial Services, and Transportation-HUD — were close to completion in late September as a combined conference report. But the three measures that have not yet advanced in either chamber are the most problematic: Commerce-Justice-Science, State-Foreign Operations, and Homeland Security, where the wall fight is being litigated.

The House met Trump’s demand with $5 billion in its DHS measure for border barriers and associated infrastructure and technology, while the Senate included only $1.6 billion. Senate appropriators must figure out if they can come up with extra money for the wall without shortchanging bipartisan priorities and triggering a Democratic filibuster.

Where to find the additional funds to meet Trump’s demand without shortchanging bipartisan Senate funding priorities — and how to satisfy Trump’s signature campaign promise without angering the Democratic base — is the biggest remaining stumbling block to completing the fiscal 2019 appropriations process.

“I think it’s going to be difficult, but we’ll just have to see,” said Sen. Shelley Moore Capito, R-W.Va., chairwoman of the Senate Homeland Security Appropriations Subcommittee.