(CNN) FBI Director Christopher Wray said Thursday that there hasn't been a coordinated national voter fraud effort in past elections, regardless of the method of voting.
"Now, we have not seen, historically, any kind of coordinated national voter fraud effort in a major election, whether it's by mail or otherwise," he said before a Senate panel in response to a question on whether voting by mail is secure.
However, there has been voter fraud at the local level "from time to time," Wray told the Senate Homeland Security and Governmental Affairs Committee during a hearing on threats to the homeland, adding that the FBI takes seriously the responsibility to investigate such fraud.
"Certainly to change a federal election outcome by mounting that kind of fraud at scale would be a major challenge for an adversary, but people should make no mistake, we're vigilant as to the threat and watching it carefully because we're in an uncharted new territory," he said.
At a House hearing last week, Wray said that Russia has been "very active" in its efforts to influence US elections, with the primary goal being to "denigrate" Democratic presidential nominee Joe Biden, echoing the intelligence community's public assessment of Moscow's meddling efforts issued last month.
President Donald Trump and several other top administration officials have recently attempted to play up the theory that China is meddling to get Biden elected, while downplaying well-founded reports that Russia is trying to help Trump win again, like it did in 2016.
Trump pushed back on Wray's comments last week, tweeting, "But Chris, you don't see any activity from China, even though it is a FAR greater threat than Russia, Russia, Russia. They will both, plus others, be able to interfere in our 2020 Election with our totally vulnerable Unsolicited (Counterfeit?) Ballot Scam. Check it out!," along with a C-SPAN link to Wray's remarks.
Trump has repeatedly dismissed Russia's ongoing election-meddling and played up the notion that China is actively meddling in the election.
The President also told reporters last week he "did not like" Wray's answers on the Hill, but wouldn't say if he were considering replacing him.
"We're looking at a lot of different things," Trump said, when asked if he would replace Wray. "And I don't -- I did not like his answers yesterday, and I'm not sure he liked them either. I'm sure that he probably would agree with me," he said on the south lawn of the White House Friday.
Trump also took issue with Wray's testimony last week about Antifa, which the FBI director -- pressed on the issue mainly by Republicans -- said is not a group or organization but rather a movement or ideology.
"We look at Antifa as more of an ideology or a movement than an organization. To be clear, we do have quite a number of properly predicated domestic terrorism investigations into violent anarchist extremists, any number of whom self-identify with the Antifa movement, and that's part of this broader group of domestic violent extremists," Wray said.
Trump wasn't satisfied. "Antifa is a bad group and they're criminals and they're anarchists and they're agitators and they're looters and rioters and everything else. They're bad and when a man doesn't say that, that bothers me. I wonder why he's not saying that," he said.
During Thursday's Senate hearing, Wray emphasized the threat from Antifa, saying some of his comments from last week's hearing were "more clearly conveyed than others."
"Antifa is a real thing, it is not a fiction," Wray said. "We have seen organized tactical activity at both the local and regional level. We have seen Antifa adherents coalescing and working together in what I would describe as small groups and nodes."
The FBI director said there are a number of investigations into violent anarchist extremists, some of whom self-identify with Antifa. He also pointed out that there are "militia types," which the FBI is investigating as well.
Wray said there are three broad categories participating in protests across the country: The largest group is peaceful protesters. There are also criminal opportunists, and then "by far and away the most dangerous," he said, are people violating federal law. Wray said motivations vary, but the FBI has seen a number of "violent anarchist extremists" participating in the mix.
"Trying to put a lot of these things into nice, neat, clean buckets is a bit of a challenge," he added.
Wray pointed out that the majority of recent protests across the country have been peaceful, adding that the FBI has opened investigations on individuals involved in "criminal activity at these protests."
"Now let me be clear, we do not investigate groups or individuals based on ideology or on the exercise of First Amendment protected activity alone, but when the ideology leads someone to commit criminal acts and pursue violence, the FBI will not hesitate to take appropriate action," he said.
White supremacists pose the most lethal terror threat to the nation, said Ken Cuccinelli, the senior official performing the duties of the Deputy Secretary, who was also testifying at the hearing, after he was questioned on why the department had softened language around the issue in recent leaked draft reports.
"When White supremacists act as terrorists, more people per incident are killed. That is a higher lethality. That's what we're referring to," he said during the Senate hearing, about the department's position on the threat.
Democratic Sen. Jacky Rosen of Nevada pressed Cuccinelli on why the recently leaked drafts of the soon-to-be-published "Homeland Threat Assessment" showed a change in the language in the assessment about White supremacy. Brian Murphy, a DHS whistleblower, alleged in a complaint that Cuccinelli directed Murphy to modify the section on White supremacy "in a manner that made the threat appear less severe, as well as include information on the prominence of violent 'left-wing' groups."
Cuccinelli denied that the department softened the language, adding, "You'll see when the final report is out...what you're describing is still in our homeland threat assessment, so your concerns in that regard I can put to rest."
When asked why he ordered Murphy to downplay the threat, Cuccinelli said, "I absolutely did not do that. That did not happen."
He also addressed another recent DHS whistleblower report that detailed a high rate of hysterectomies and alleged medical neglect in a complaint filed to the Department of Homeland Security inspector general last week.
"Those are shocking allegations and as a result I immediately dispatched a team from outside of ICE, including a doctor from the Coast Guard, an attorney, and one member of my staff who's a retired army nurse, as well to review the records at that facility," he said.
The documentation indicates two hysterectomies were performed on two women over the course of four years, he said.
This story has been updated with background about Wray's comments about Antifa last week.