U.S. Postmaster General Louis DeJoy expressed frustration Thursday to reporters about the ongoing criticism from election officials about how the agency handles mail-in ballots, saying it is wrong to suggest they could be displaced.

The U.S. Postal Service’s leader is expressing frustration with ongoing criticism of how it handles mail ballots.

Postmaster General Louis DeJoy pledged Thursday that the US Postal Service will undertake “heroic efforts” to deliver all mail-in ballots on time this year and urged people to put their ballots in the mail at least one week before Election Day on November 5.