President Donald Trump tweeted on Sunday that if he does not get funding for border security, including a promised wall between the United States and Mexico, then he will consider shutting down the government.

"I would be willing to 'shut down' government if the Democrats do not give us the votes for Border Security, which includes the Wall!" Trump tweeted. "Must get rid of Lottery, Catch & Release etc. and finally go to system of Immigration based on MERIT! "We need great people coming into our Country!"  

Government funding expires on Sept. 30 at midnight, 37 days before the midterm elections in November, something that has been making Republicans nervous.

While congressional Republicans say they are not expecting a shutdown a few weeks before the midterm elections, Senate Republicans did pass several funding bills on Wednesday with the aim of keeping the government running when current funding runs out in September.

According to a story from Politico, both Senate Majority Leader Mitch McConnell (R-Kentucky), and Speaker of the House Paul Ryan, (R-Wisconsin), say they believe the president will hold off on a full-fledged fight over a border wall until after the election. 

McConnell, said in an interview last week that a government shutdown only a little more than a month before the Nov. 6 elections “won’t happen.”

It is not the first time the president has threatened a shutdown. In January of this year, the government shut down briefly before he signed a $400 billion budget deal.

So, what would happen if the president refuses to sign the legislation to fund the government on the last day of September?