The US Postal Service has suspended new policies that were decried as an attempt to sabotage the 2020 election.
Postmaster General Louis DeJoy said on Tuesday he would reverse operations changes that critics say would hamper mail-in voting.
The u-turn comes as Mr DeJoy is due to testify to Congress and at least 20 states were preparing to sue.
There is a fierce debate over postal funding in 2020, as record numbers of Americans are expected to vote by mail.
The US Postal Service (USPS) under Mr DeJoy had begun what it said were cost-cutting measures in recent months.
However, in a sharp reversal, Mr DeJoy has now said that post office hours would not be cut and no further post boxes or sorting machines would be removed.
Mr DeJoy, a former Republican donor, also said overtime pay would continue to be approved to ensure deliveries arrive on time.
“To avoid even the appearance of any impact on election mail, I am suspending these initiatives until after the election is concluded,” Mr DeJoy said in a statement.
What is US row over postal service about?
For more updates on this story, see bbc.com.