At least 20 states plan to file lawsuits this week against the U.S. Postal Service and its new postmaster, Louis DeJoy, seeking to reverse service changes that have prompted widespread reports of delays and accusations of an intentional effort to thwart voters from mailing their ballots this fall.

The suits, expected to be filed in federal court imminently, will argue that the Postal Service broke the law by making operational changes without first seeking approval from the Postal Regulatory Commission. They will also argue that the changes will impede states’ ability to run free and fair elections, officials from several state attorney general offices told The Washington Post.

“We’re trying to stop Trump’s attacks on the Postal Service, which we believe to be an attack on the integrity of election. It’s a straight-up attack on democracy,” Maryland Attorney General Brian Frosh (D) said in an interview. “This conduct is illegal. It’s unconstitutional. It’s harmful to the country. It’s harmful to individuals.”

“We’re asking a court to make him stop,” he said.