House Speaker Nancy Pelosi is calling lawmakers back early from their August recess to vote on legislation that would block the U.S. Postal Service from making operational changes.

In a letter for House Democrats on Sunday, Pelosi said lawmakers will vote later this week on the Delivering for America Act, introduced by Rep. Carolyn B. Maloney of New York, which "prohibits the Postal Service from implementing any changes to operations or level of service it had in place on January 1, 2020."

Since taking over in mid-June, Postmaster General Louis DeJoy has implemented a series of changes he says are aimed at cutting costs and improving efficiency. But those changes have alarmed postal workers and their unions, who cautioned that the new policies will increase delays and make it harder for workers to do their jobs.

Pelosi said President Trump was instituting a "campaign to sabotage the election by manipulating the Postal Service to disenfranchise voters." She said DeJoy, a major donor to President Trump and Republican campaigns, is pushing to "degrade postal service, delay the mail, and — according to the Postal Service itself — threaten to deny the ability of eligible Americans to cast their votes through the mail in the upcoming elections in a timely fashion."

Reports in recent days have found the Postal Service was removing mail collection boxes and high-speed mail sorting machines. (In a statement to NPR Sunday, a postal service spokesperson said collection box removal will cease for the next 90 days "while we evaluate our customers concerns.") Under DeJoy, postal employees have been barred from working overtime and had to let some mail go undelivered until the next day. Mail delays have since been reported across the country.

Pelosi also called for House Democrats to participate in a "day of action" on Tuesday and hold press events at post offices in their districts.

Earlier on Sunday, Maloney, who chairs the House Oversight Committee, called for an "urgent" hearing into the Postal Service changes. In a letter to DeJoy, Maloney asked the postmaster general to explain why he had made so many changes with less than three months to go until the upcoming presidential election.

"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," Maloney wrote.

"Your testimony is particularly urgent given the troubling influx of reports of widespread delays at postal facilities across the country — as well as President Trump's explicit admission last week that he has been blocking critical coronavirus funding for the Postal Service in order to impair mail-in voting efforts for the upcoming elections in November."

Maloney also called for Robert Duncan, chairman of the U.S. Postal Service Board of Governors, to appear at the Aug. 24 hearing.

The attention to the Postal Service has been amplified by President Trump, who has attacked mail-in voting and said on Thursday that he opposed more funding for the Postal Service because it would help people vote by mail.

In late July the Postal Service warned election officials in almost every state that the Postal Service may not be able to deliver some mail-in ballots in time to be counted according to those states' election laws.

About 100 people demonstrated outside DeJoy's house in Washington on Saturday to protest the changes. Another protest took place Sunday at his home in Greensboro, N.C.

NPR's Vanessa Romo contributed to this report.

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