President Trump slammed Democrats Tuesday, suggesting they want to “shut down the Government,” just days before the deadline, underscoring his non-negotiable campaign promise to build a “great WALL” along the U.S.-Mexico border.

“We must have Security at our VERY DANGEROUS SOUTHERN BORDER, and we must have a great WALL to help protect us, and to help stop the massive inflow of drugs pouring into our country!” Trump tweeted Tuesday morning.

Minutes later, he tweeted again, pushing for a “merit based” immigration system.

“The Democrats want to shut down the Government over Amnesty for all and Border Security. The biggest loser will be our rapidly rebuilding Military, at a time we need it more than ever. We need a merit based system of immigration, and we need it now! No more dangerous lottery,” Trump tweeted.

On Friday at 11:59:59 p.m. ET, the funding to keep the federal government running expires. If congressional lawmakers cannot come to a bipartisan agreement, the government will close on Jan. 20—the one year anniversary of Trump taking office.

Congressional lawmakers, on both sides of the aisle, have punted a long-term budget solution, and have continued to pass just short-term stop-gap spending deals as they negotiate their policy must-haves.

The president has accused Democrats of blocking any agreement on a spending bill, due to their demands of preserving the Obama-era Deferred Action on Childhood Arrivals—the program that protects immigrants brought to the U.S. illegally as children from deportation.

Republicans, though, are looking for increased defense funding, and for border security—including changes to the so-called Visa Lottery System and to “chain migration” programs. The president has argued that the wall along the southern border must be included in any comprehensive immigration reform deal.

Fox News’ Chad Pergram contributed to this report.