Speaker Nancy Pelosi is calling House lawmakers back to Washington this coming week to vote on legislation to bar the U.S. Postal Service from implementing changes to “operations or level of service.”

A vote could come as soon as Saturday, Aug. 22, according to a senior Democratic aide. That would mean a rare weekend session that would interrupt the traditional summer recess. The House wasn’t originally scheduled to return for floor votes until Sept. 14, barring the need to take up a coronavirus relief bill before then.

In a “Dear Colleague” letter Sunday evening, Pelosi said that the House’s return is in response to “devastating effects” of what she called President Donald Trump’s “campaign to sabotage the election by manipulating the Postal Service to disenfranchise voters.”

Trump said Thursday he opposed emergency funding for election operations and the Postal Service because it could allow more people to vote by mail.

House Majority Leader Steny H. Hoyer is expected to announce full details of the return schedule and legislative agenda on a Monday morning call with the Democratic Caucus.

The House Oversight and Reform Committee has called on U.S. Postmaster General Louis DeJoy, a major donor to Trump’s campaign, to testify on Monday, Aug. 24, regarding major organizational and operational changes he’s implemented since he took the top Postal Service job in May.

“Over the past several weeks, there have been startling new revelations about the scope and gravity of operational changes you are implementing at hundreds of postal facilities without consulting adequately with Congress, the Postal Regulatory Commission, or the Board of Governors,” Oversight Chairwoman Carolyn B. Maloney wrote to DeJoy.

Service changes imposed by DeJoy last month include orders that mail be kept until the next day if postal distribution centers are running late and the elimination of overtime for hundreds of thousands of postal workers.

Under Maloney’s bill that the House is planning to take up, postal services and operations that were in place on Jan. 1, 2020, would have to be restored and maintained through 2021 or the end of the COVID-19 public health emergency, whichever comes later. That would include undoing changes to overtime pay policies, service standards and closures of post offices or processing facilities.

Widespread mail delays have prompted concerns about mail-in voting this fall. Record numbers of voters are expected to cast mail-in ballots due to the pandemic.

[The 2020 fight over the Postal Service underscores its long-unaddressed challenges]

Pelosi also asked members to hold media events Tuesday at post offices in their districts, for a mass show of action to raise awareness.

Senate Minority Leader Charles E. Schumer called on his GOP counterpart, Majority Leader Mitch McConnell, to bring the Senate back for a vote on the bill after it passes the House.

“I call on Leader McConnell to bring the Senate back into session to quickly act on the House’s legislation that will undo the extensive damage Mr. DeJoy has done at the Postal Service so that people can get their paychecks, medicines, and other necessities delivered on time, and to ensure our elections will remain completely free and fair,” the New York Democrat said in a statement Sunday evening.

Earlier in the day, Schumer previewed the possibility of the House being called back during a news conference in New York City. “Speaker Pelosi and I are looking at having a standalone bill,” he said.

Schumer said he also wants legislation that would require all election mail to be treated as first-class mail regardless of the applicable postage rate. He said the mail sorting machines would need to be put back in service and overtime hours would need to be restored.

“Our legislation will demand it, and we will put that legislation on the COVID [relief] bill or some other must-pass bill,” Schumer said.

Without any agreement on a coronavirus relief package at hand, the next such must-pass bill may be a continuing resolution that would be needed to keep the government open past Sept. 30, though states will have already begun mailing fall absentee ballots before that deadline.

Schumer said DeJoy should also testify before the Senate Homeland Security and Governmental Affairs Committee, in addition to appearing before the House Oversight panel.

“If Mr. DeJoy refuses to appear, he should be stamped return to sender,” Schumer said. “He shouldn’t be allowed to be the postmaster general if after all this destruction, he can’t answer to the American people what he is doing.”