New Delhi, Sept. 2 -- A whistleblower has warned Congress that the US Postal Service is moving ahead with a new system to enforce President Donald Trump's restrictions on mail-in voting, raising concerns that technical errors could lead to legitimate ballots being rejected or delayed.

The allegations have drawn scrutiny from Democratic Senator Richard Blumenthal, who has asked Postmaster General David Steiner to provide documents and answer questions about the system.

According to the whistleblower's claims cited by Blumenthal, USPS is preparing a system with what the senator described as an "impracticable zero percent failure rate."

Under the system, even a single problem matching a ballot to an approved voter could potentially affect...