Nineteen Democratic attorneys general sued Thursday over President Trump’s executive order that aims to strengthen proof of citizenship requirements in voting and prevent states from tabulating mail-in ballots received after Election Day. 

The new lawsuit adds to three existing cases filed by the Democratic National Committee (DNC) and separate coalitions of private groups, who accuse Trump of going beyond his authority and violating the separation of powers.

“It bears emphasizing: the President has no power to do any of this,” the states’ complaint reads. “Neither the Constitution nor Congress has authorized the President to impose documentary proof of citizenship requirements or to modify State mail-ballot procedures.”

Trump’s order, signed March 25, directs the attorney general to target states that count absentee or mail-in ballots that are received after Election Day, a practice that conservatives have increasingly targeted in recent years. Court battles over whether it is legal commenced long before Trump’s inauguration. 

The president also directed that the federal mail voter registration form and the postcard application used by voters overseas require citizenship proof of citizenship. 

“If instead Plaintiff States choose not to comply with the President’s blatantly unconstitutional attempt to legislate-by-fiat, they will suffer severe cuts in federal funding that will throw the national electoral system into disarray. The Framers carefully crafted a federal compact that protects the States from this Hobson’s choice,” the lawsuit states. 

The White House has previously pushed back on the legal challenges, saying Trump’s order is “an effort to protect the integrity of American elections” and that “Democrats continue to show their disdain for the Constitution.” 

Led by California and Nevada, the states suing are Massachusetts, Arizona, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, New Jersey, New Mexico, New York, Rhode Island, Vermont and Wisconsin. 

The new case adds to three separate challenges filed earlier this week that include plaintiffs like the DNC, the NAACP and the League of United Latin American Citizens.