"We have not seen, historically, any kind of coordinated national voter fraud effort in a major election, whether it is by mail or otherwise," Wray said.
Wray assured the Committee that the US voting system for national elections remains secure and that the FBI and other federal law enforcement agencies were closely monitoring this year's process for any signs of fraud.
"We have not seen, historically, any coordinated national voter fraud in a major election. We have seen voter fraud in a local election from time to time. ... We are vigilant as to the threat and watching it carefully. We are in uncharted new territory," Wray said.
The continuing novel coronavirus pandemic has led to an unprecedented number of requests for mail-in voting, to avoid the risk of infection at polling stations. Some states have ruled mail-in voting as mandatory. President Donald Trump has repeatedly expressed his fear that the system could offer an opportunity to fake or dispute election results.