Two Colorado presidential electors have filed a new federal lawsuit against Secretary of State Wayne Williams, saying that threats he made leading up to last year’s dramatic Electoral College vote violated their constitutional rights.

The lawsuit was announced Tuesday by Equal Citizens, an advocacy group, on behalf of two Democratic electors, Polly Baca and Robert Nemanich, who argue that the U.S. Constitution gives presidential electors the right to vote their conscience.

That right, they said, was violated when Williams adopted a new policy aimed at compelling them to vote for the winner of the state’s popular vote, Hillary Clinton.

“Polly Baca and Robert Nemanich believed the special circumstances of the last election required that they vote their conscience, contrary to a pre-election pledge,” Larry Lessig, one of their attorneys, said in a statement announcing the lawsuit.

“Secretary Williams took the egregious step of threatening them with removal, as well as criminal prosecution, if they did so.”

The lawsuit in U.S. District Court is the latest in a series of legal challenges to Colorado’s electoral rules, which require presidential electors to vote for the winner of the state’s popular vote.

The Electoral College voting process — often a ceremonial affair — took on new importance after Donald Trump’s election as president last November because a group of Democratic electors had sought to band together with Republicans to deny Trump the 270 electoral votes he needed to become president.

That effort, of course, failed. But Colorado became an unlikely ground zero for a broader debate about the role of the Electoral College.

Baca and Nemanich in December filed a federal lawsuit challenging a Colorado state law that requires presidential electors to vote for the winner of the popular vote, saying that the founders intended for electors to be able to vote their conscience.

They ultimately voted for Hillary Clinton, as state law requires. But a third elector, Micheal Baca, actually followed through with a plan to vote for Ohio Gov. John Kasich. That vote was thrown out, a replacement elector was appointed and the Attorney General’s Office is now investigating possible criminal charges.

Suzanne Staiert, deputy secretary of state, said the latest lawsuit is without merit.

“They made a voluntary decision to take the oath and follow the law,” Staiert said. “It looks like they’re just grandstanding and engaged in the same kind of gamesmanship that they engaged in last December.”

The suit seeks attorneys fees and unspecified damages against Williams for violating the electors’ voting rights.

“Regardless, it is critical that the question of whether electors must vote based on their pledge, or are free to vote their conscience, is settled before the 2020 election,” Lessig said.