Tim Kaine
Tim KaineReuters

Senator Tim Kaine (D-VA), Democratic presidential candidate Hillary Clinton’s running mate, suggested Saturday that some officials at the FBI are “actively working” to support Republican presidential candidate Donald Trump, The Washington Post reports.

Kaine’s claim came during an interview with the Miami-based television network Fusion. The comments mark an escalation in the Clinton campaign's response to the FBI's renewed inquiry into Clinton's use of a private email server when she served as Secretary of State.

FBI Director James Comey's disclosure of the renewed probe in a letter to senior lawmakers just days before the elections raised questions about his motives and drew criticism from some – mostly Clinton supporters – over his timing.

In Saturday’s interview, Kaine called the FBI a “leaky sieve” and accused Comey of breaking agency protocol by discussing a politically sensitive case so close to an election.

He also dismissed former New York mayor Rudolph Giuliani’s decision to back off claims that he, Giuliani, had been given advance notice of the FBI's plans to possibly reopen the Clinton investigation.

“I don’t think Giuliani’s walk-back is credible,” Kaine said, according to The Washington Post. “I think the FBI sadly has become like a leaky sieve.”

Giuliani, a supporter of Trump, told Fox News in the days before Comey alerted lawmakers to the FBI's renewed inquiry that there would be a “big surprise” coming from the agency. Asked about his claims again on Friday, Giuliani said, “You’re darn right I heard something.”

Giuliani pulled back on Saturday, saying he was aware only of “tremendous anger” among former FBI agents at Comey.

Kaine asserted on Saturday that Comey's decision to alert Congress about his review of the Clinton case “suggests that it’s probably more likely explained that [Comey] knew that the FBI is not only a leaky sieve but there were people within the FBI actively working — actively working — to try to help the Trump campaign.”

“This is just absolutely staggering, and it is a massive blow to the integrity of [the FBI],” he added.

Law enforcement sources indicated last week that Comey was worried over possible leaks from within his agency and therefore decided to tell Congress on his own that the FBI was investigating newly discovered emails related to Clinton.

Kaine said he thinks Comey was under pressure to release information to Congress because “subordinates would do it if he didn’t.”

The Clinton campaign has publicly questioned Comey's motives in making the announcement as well as his fitness to serve — despite praising his leadership of the FBI after he announced in July that the agency would not recommend the email case for prosecution. Clinton herself has raised the issue on the stump, while top aides and surrogates have called Comey's judgment into question.