Democrats are scrambling to reverse changes that have slowed mail delivery.

In yet another sign of mounting legal pressure on the beleaguered mail agency, New York Attorney General Letitia James led a coalition of states and cities on Tuesday in suing the U.S. Postal Service, its controversial leader, and President Donald Trump over a set of cost-cutting initiatives that have slowed mail delivery service in parts of the country.

The suit accuses Postmaster General Louis DeJoy of violating federal and constitutional statutes by failing to seek approval for the changes, which include limiting mail carrier trips and overhauling the agency’s reporting structure, from a regulatory board with oversight of the agency. It seeks to reverse those changes and prevent any future disruptions in service.

James also asserts in the lawsuit, which was joined by New Jersey, Hawaii, New York City, and San Francisco, that DeJoy enacted the overhaul “in ways that align with the President’s campaign against mail-in voting,” according to her complaint. The president has engaged in a broadside attack against the Postal Service in recent months, calling it “a joke,” and peddled unsubstantiated claims that absentee voting will lead to election fraud.

“This USPS slowdown is nothing more than a voter suppression tactic,” James said in a statement. “We will do everything in our power to stop the president’s power grab and ensure every eligible voter has the opportunity to cast a ballot come November.”

Last week, DeJoy announced plans to suspend several of the initiatives he put in place until after the November elections, “to avoid even the appearance of any impact on election mail.” But despite his assurances, Democrats at the state level and in Congress have sought to hold DeJoy to his word.

“We can’t take DeJoy’s statements at face value,” wrote Rep. Ro Khanna, D-Calif., in a tweet on Tuesday.

Earlier this month, Democratic state attorneys general filed a separate suit targeting the Postal Service over the changes, which they said hamper the states’ abilities to conduct free elections.

On Capitol Hill, lawmakers have heard testimony from DeJoy twice in the past week. In a combative hearing on Monday before the House Oversight and Reform Committee, DeJoy continued to defend his handling of the postal agency and reiterated that he would not reinstall mail sorting machines that had been decommissioned in recent months.

The committee chairwoman, Rep. Carolyn Maloney, D-N.Y., presented evidence that laid out mail delivery disruptions beginning in July, shortly after DeJoy took the agency’s helm and began his overhaul. Maloney threatened DeJoy with a subpoena and accused him of withholding information from the oversight panel.

The Postal Service declined to comment on the new lawsuit, referring ABC News to the postmaster general’s testimony.