Sen. Ed Markey (D-Mass.) is calling on President Donald Trump’s Cabinet and Vice President JD Vance to remove him from office via the 25th Amendment of the U.S. Constitution over his latest threat to Greenland.

“Invoke the 25th Amendment,” Markey replied, referring to a constitutional process by which the vice president and a majority of the Cabinet can declare a president unable to perform his duties. If the president contests that declaration, Congress would ultimately decide whether he remains in power.

While Greenland is a semi-autonomous Danish territory, Trump said earlier this month that “one way or the other, we’re going to have Greenland” and has repeatedly refused to rule out the use of military force.

That was enough for Markey and at least three other U.S. lawmakers. Rep. Eric Swalwell (D-Calif.), Rep. Sydney Kamlager-Dove (D-Calif.) and Rep. Yassamin Ansari (D-Ariz.) also called for the 25th Amendment to be invoked, with Ansari explicitly describing Trump as “extremely mentally ill.”

Others on social media also demanded that the 25th Amendment be invoked: