WASHINGTON (Reuters) - President Donald Trump on Tuesday invited Republican and Democratic congressional leaders to a border security briefing at the White House as the federal government remained partially shut down over his demand to fund a wall along the U.S.-Mexico border.

FILE PHOTO: The border wall divides Tijuana, Mexico on the left and San Diego County, California, U.S. November 17, 2018. Picture taken November 17, 2018. REUTERS/Adrees Latif

The president’s invitation, which was described by congressional sources as a briefing and not a negotiating session, was sent to the top two Democrats and Republicans in both the Senate and the House of Representatives.

Republican Senate Majority Leader Mitch McConnell’s office said he would attend the briefing, which is set for Wednesday. It was unclear whether the other leaders would participate, one source said.

The White House did not immediately respond to a request for comment on the specifics of the briefing.

The House and Senate will reconvene briefly on Wednesday to mark the last day of the Republican-controlled 2017-2018 Congress, with no signs of a workable plan to end the shutdown, which is now in its second week.

About a quarter of the federal government is shut down, with roughly 800,000 workers affected.

Democrats, who won control of the House in the November elections, plan to approve on Thursday a two-part spending package meant to end the shutdown. But its prospects are grim in the Republican-led Senate, which previously approved similar measures on the floor or in committee but has since fallen in line with Trump’s demands for funding for the border wall.

The legislation will set the stage for the first major battle of the new Congress between House Democrats led by Nancy Pelosi and Senate Republicans led by McConnell.

“We are giving the Republicans the opportunity to take yes for an answer,” Pelosi, who is expected to be the House speaker, said in a letter to colleagues released by her office on Tuesday.

“Senate Republicans have already supported this legislation, and if they reject it now, they will be fully complicit in chaos and destruction of the president’s third shutdown of his term.”

Trump triggered the shutdown, which began on Dec. 22, by insisting that $5 billion in funding for the border wall be part of any spending measure.

“Border Security and the Wall ‘thing’ and Shutdown is not where Nancy Pelosi wanted to start her tenure as Speaker! Let’s make a deal?” Trump tweeted on Tuesday.

Trump calls the wall crucial to curbing illegal immigration, echoing his 2016 presidential campaign pledge. During his run for the White House, Trump insisted Mexico would pay for the wall.

The Democrats’ two-part spending package includes a bill to fund the Department of Homeland Security at current levels through Feb. 8 and provide $1.3 billion for border fencing and $300 million for other border security items including technology and cameras.

The second part of the package would fund federal agencies that are now unfunded, such as the Justice, Commerce and Transportation departments, through Sept. 30, the end of the federal fiscal year.

The House Democrats’ measure does not contain the $5 billion Trump wants in wall funding. McConnell has said Senate Republicans will not approve a spending measure not supported by Trump.