US President Donald Trump. Mark Wilson/Getty Images President Donald Trump suggested Tuesday that FBI Director James Comey gave Hillary Clinton a "free pass" during the 2016 presidential election. In a series of tweets late Tuesday night, Trump said Comey was the "best thing that ever happened" to his former campaign rival.

"He gave her a free pass for many bad deeds," the president declared, suggesting the agency's decision not to bring charges against Clinton for her use of a private email server was equivalent to avoiding what Trump believes is a deserved punishment for Clinton's actions.

Trump also repeated his claim that the multiple federal investigations surrounding Russia's meddling in the US election are motivated by the Democrats' defeat. That claim has been summarily rejected, due in part to mounting evidence to the contrary from US intelligence agencies.

The president's tweets appeared to be referencing remarks Clinton made earlier Tuesday during a sit-down with CNN's Christiane Amanpour, in which Clinton talked about circumstances that led to her losing the election.

The former presidential candidate and secretary of state took "absolute personal responsibility" for the defeat, but added "a combination of Jim Comey's letter on October 28 and Russian WikiLeaks raised doubts in the minds of people who were inclined to vote for me and got scared off."

"As Nate Silver has concluded, if the election had been on October 27, I would be your president," Clinton said.

Comey is set to testify Wednesday before the Senate Judiciary Committee in a hearing on FBI oversight.