While negotiations between President Trump and Congressional Democrats have thus far come to naught, there is at least one way Congress can unilaterally reopen the government with out the commander-in-chief: veto override.

What does this mean?

Let’s review the two ways a bill can become law. The first, more common way is for a bill to be passed by both the House and Senate and then signed by the president. The second option, in which the president vetoes a bill approved by both houses, allows Congress to override his veto by re-passing the bill with two-thirds of each chamber.

And Congress theoretically has the votes to do just that.

Last month, before the government shut down, the Republican-controlled Senate passed a stopgap bill that would have kept the government funded through February, but did not include money for the border wall. The bill passed by voice vote, meaning that none of the 100 senators demanded a roll call vote.

While the Republican-controlled House at the time refused to vote on the bill, the new Democratic-led House has already introduced and passed bills to fund various parts of the government currently impacted by the shutdown.

To enact such legislation, these House-passed bills would need to be approved by the Senate. Even if Trump were to veto them, if the bills were then re-passed with two-thirds of both the House and Senate, Congress could end the government shutdown.

The main obstacle in Congress’ way now is a reversal from Senate Majority Leader Mitch McConnell, who announced Wednesday that he will not allow a vote on any bill that doesn’t have Trump’s support. Speaking on the Senate floor, McConnell said the chamber “will not waste its time considering a Democratic bill which cannot pass this Chamber and which the President will not sign.”