Top US lawyer quits over ‘vote fraud’ memo
Any such cases would normally be the remit of individual states, but Mr Barr said this was not a hard and fast rule.
Donald Trump refuses to accept Joe Biden’s projected victory, and has made unsubstantiated fraud claims.
The president’s campaign is seeking an emergency injunction in Pennsylvania to prevent Mr Biden’s victory being certified in the state.
The president-elect’s projected win there on Saturday took him over the threshold of 270 electoral college votes needed to secure victory nationwide.
Mr Trump’s spokeswoman vowed the legal battle to contest Mr Biden’s victory was only just beginning.
“This election is not over,” White House press secretary Kayleigh McEnany told a news conference. “Far from it.”
Mr Barr said prosecutors should only look into “substantial allegations” of irregularities, and that “specious, speculative, fanciful or far-fetched claims” should be ignored.
He acknowledged that individual states had the primary responsibility for the conduct of elections but said the justice department had “an obligation to ensure that federal elections are conducted in such a way that the American people can have full confidence in their electoral process and their government”.