WASHINGTON, D.C. (REUTERS) — On Monday President Trump denied trying to undermine the Postal Service’s ability to handle a flood of mail-in ballots ahead of the November election, as Democrats prepared to move against changes his administration has set in motion.

“No, we’re not tampering,” Trump said in an interview with Fox News amid an outcry from Democrats and other critics who accuse him of trying to hamstring the Postal Service to suppress mail-in voting as he trails Democratic presidential challenger Joe Biden in opinion polls.

“We want to make it run efficiently, run good. We want to make it for less money, much better, always taking care of our postal workers,” the Republican president said, describing the Postal Service as “one of the disasters of the world.”

Trump also expressed support for expanded in-person voting, including more voting booths, early voting and other efforts, while he reiterated his attacks on mail-in voting. Trump has claimed repeatedly and without evidence that a surge in mail-in voting would lead to fraud in the Nov. 3 election.

Voting by mail is nothing new in the United States, and one in four voters cast ballots that way in 2016.

Democrats in Congress, alarmed at Postal Service changes put in motion under Trump with the election looming, continued to step up pressure on the president and Postmaster General Louis DeJoy, a major Trump political donor.

Democrats, who control the House of Representatives, were due to hold a conference call to discuss expected plans to vote on Saturday on legislation that would prohibit changes to Postal Service levels that were in place on Jan. 1.

Concerned by the cuts coming in a year when up to half of U.S. voters could cast ballots by mail, Democrats have pointed specifically to reductions in overtime, restrictions on extra mail transportation trips and new mail sorting and delivery policies as changed that threaten to slow mail delivery.

House Democratic Conference Chairman Hakeem Jeffries and Representative Ted Lieu also called on the FBI to open a criminal probe into DeJoy.

“There is evidence that making mail-in balloting more difficult may be one of the motivations for the changes instituted at the Post Office,” Jeffries and Lieu wrote in a Monday letter to FBI Director Christopher Wray.

“There is also evidence that the postmaster general has a financial stake in multiple financial entities that are either competitors to or contractors for the Post Office,” the lawmakers added.

Several Democratic state attorneys general also considering potential legal action to stop Postal Service changes that could affect the election outcome.

Top Democrats in Congress called on DeJoy and another top postal official to testify next week at a hearing on Postal Service policy changes.