President Trump warned Friday that a partial government shutdown would last “for a very long time” if Congress does not meet his demand Friday for billions in funding for his long-promised border wall in a stopgap spending measure.

In a spate of morning tweets, Trump sought to pin blame on Democrats for a potential shutdown even though he said last week that he would proudly own one if lawmakers did not provide at least $5 billion toward his marquee campaign promise.

And he suggested that Senate rules should be changed so that Republicans could pass the bill without any Democratic support ? a move that a spokesman for Senate Majority Leader Mitch McConnell (R-Ky) promptly dismissed.

“The Democrats, whose votes we need in the Senate, will probably vote against Border Security and the Wall even though they know it is DESPERATELY NEEDED,” Trump wrote. “If the Dems vote no, there will be a shutdown that will last for a very long time. People don’t want Open Borders and Crime!”

Trump’s warning came ahead of a midnight deadline for the president and Congress to come to terms on a spending bill to avert a partial government shutdown that would affect funding for roughly 25 percent of the federal agencies whose budgets rely on Congress.

As the shutdown loomed, Trump invited a group of Senate Republicans to the White House for a meeting.

After Trump threatened Thursday to veto a Senate measure that did not contain the border funding he sought, the House hurried to appease the president, pulling together a bill that would keep the government funded through Feb. 8 while also allocating $5.7 billion for the border wall. The House bill also included nearly $8 billion for disaster relief for hurricanes and wildfires.

Democrats, however, have enough votes in the Senate to keep that bill from advancing and have showed no signs of relenting.

“You own the shutdown?your own words, @realDonaldTrump,” Senate Minority Leader Charles E. Schumer (D-N.Y.) said in a tweet Friday morning. “The Senate UNANIMOUSLY passed a bipartisan solution to avoid a shutdown. Then you threw another temper tantrum and convinced the House to ignore that compromise. #TrumpShutdown”

In a contentious Oval Office meeting last week with Schumer and House Minority Leader Nancy Pelosi (D-Calif.), Trump said he would be “proud to shut down the government for border security.”

“So I will take the mantle,” he said. “I will be the one to shut it down. I won’t blame you for it.”

“The Democrats now own the shutdown!” Trump insisted in one of his Friday morning tweets.

In other tweets Friday, Trump urged McConnell to “fight for the Wall and Border Security as hard as he fought for anything.”

Trump also urged McConnell to “use the Nuclear Option and get it done!”

That was a reference to a Senate rule that requires 60 votes to advance most legislation. Trump was advocating that McConnell change the rule so that only 51 votes are required. By doing that, Republicans would be able to pass a bill without Democratic cooperation in a chamber in which Republicans hold 51 seats.

But a McConnell spokesman soon put out a statement making clear that wouldn’t happen.

“The Leader has said for years that the votes are not there in the Conference to use the nuclear option,” said McConnell spokesman David Popp. “Just this morning, several Senators put out statements confirming that there is not a majority in the conference to go down that road.”

For more than a year, Trump has tried to pressure McConnell to change Senate rules in a way that would allow the chamber to pass legislation with a simple majority.

During the Obama administration, when Democrats controlled the Senate, Democrats changed the rules to allow most presidential nominees to advance with a simple majority of votes. During the beginning of the Trump administration, McConnell extended this practice to the nomination of Supreme Court justices, which proved crucial because both of Trump’s nominees to the nation’s highest court won approval by a narrow margin.

But McConnell has resisted such a change for legislation, as have a number of other Republicans, worried about the precedent it would set.

Last year, more than 60 senators from both parties signed a letter to McConnell and Schumer, saying they opposed changing the rules in the way Trump has demanded. The letter was signed by, among others, Republican Sens. Susan Collins of Maine, Roy Blunt of Missouri and John Thune of South Dakota.

After Trump’s tweet on Friday, Sen. Lamar Alexander (R-Tenn.) was among those who urged colleagues not to agree to the president’s demand.

“We have rules to follow,” Alexander said in a statement. “I want to put a stop to this practice of the Senate breaking its rules to change its rules. I will not vote to turn the Senate into a rule-breaking institution and I hope that my colleagues will not.”

In his tweets, Trump also sought to counter Democratic arguments that a border wall is an antiquated strategy for curbing illegal border crossings.

“The Democrats are trying to belittle the concept of a Wall, calling it old fashioned,” Trump wrote. “The fact is there is nothing else’s that will work, and that has been true for thousands of years. It’s like the wheel, there is nothing better.”

“Properly designed and built Walls work, and the Democrats are lying when they say they don’t,” the president added.

Trump’s Twitter attacks came as a number of federal agencies were in the final stages of implementing their shutdown plans.

A number of federal parks and monuments are slated to close, some as soon as Saturday morning. The Securities and Exchange Commission posted a list of the services it will soon suspend, including the processing of certain business records. The Justice Department, Commerce Department and Internal Revenue Service are preparing to send thousands of people home without pay.

And Trump’s prediction that a shutdown would last “for a very long time” means that more than 100,000 federal employees risk missing at least one paycheck, and possibly more. Even the Border Patrol agents and Transportation Security Agency officials who are directed to continue working during the shutdown will not be paid until Congress funds their agencies.

About 480,000 federal workers would be furloughed, according to a Washington Post projection.

There were signs that some federal agencies were still making last-minute changes to their shutdown plans, adding to the confusion among federal workers.

Commerce Secretary Wilbur Ross sent an email to employees on Friday morning declaring that the agency was still “working to update our contingency plans for executing an orderly shutdown of activities.”

Seung Min Kim and Erica Werner contributed to this report.