The head of the US Postal Service has vowed the agency is "fully capable and committed" to handling the nation's mail-in votes for November's election.
Postmaster General Louis DeJoy told lawmakers that postal votes will continue to be prioritised and that recent policy changes were not made in attempt to influence the 2020 election.
Democrats say new delivery policies could lead to issues with postal votes.
The row quickly became a top campaign issue in the past two weeks.
Mr DeJoy, a top Republican donor and former logistics executive appointed to lead the agency in May, told a senate panel on Friday that the delivery changes – which have drastically slowed deliveries – were based on a "data-driven" review of mail volume.
He addressed the Republican-led Senate Homeland Security and Governmental Affairs committee amid a public furore to the changes, and amid concerns that they were made to help re-elect US President Donald Trump.
During the hearing, Mr DeJoy fended off criticism from lawmakers who said they were concerned that the removal of mail sorting machines and post boxes would lead to millions of ballots being delivered too late to be counted on election day.
Mr DeJoy told lawmakers that he is "extremely highly confident" that ballots sent back to state election officials shortly before election day on 3 November will still be delivered on time.
It comes after the US Postal Service (USPS) sent letters to states warning that mail delays may mean that millions of ballots are unable to be returned by the deadline.
"There have been no changes to any policies with regard to election mail," he told lawmakers, adding: "The postal service is fully capable and committed to delivering the nation's election mail fully and on time."
Why is there a political row over the mail?
Slower mail delivery times in the US have raised concerns about how one of the oldest and most trusted institutions in the US can handle an unprecedented influx of mail-in ballots in November's election.
This year fewer voters are expected to vote in-person amid the coronavirus pandemic, in which the US has seen the highest number of deaths and infections in the world.
That drop-off is expected to lead to an unprecedented influx of voters submitting their ballot by mail.
What is happening in Congress?
During the hearing, Mr DeJoy denied he had spoken to Mr Trump about the changes, said that he himself has voted by mail "for a number of years" and called any attempt to interfere in the election "outrageous".Read More – Source