Vermont Sen. Bernie Sanders ripped into David Brock, the head of the pro-Hillary Clinton super PAC, Correct the Record, after being asked about rumors on Thursday that his campaign was planning to bus out-of-state students into Iowa to take part in Monday’s caucuses.

Sanders let his questioner, Bloomberg Politics editor Al Hunt, have it as well.

“The Clinton people say that they are, in places like Ames and Iowa City, that they are very worried that a number of out-of-state young people may try to show up to the caucus and they’re going to make a major effort to make sure that that’s not the case,” Hunt said to Sanders in an editorial meeting held Thursday.

The newsman smirked and shrugged as he asked the question, but provided no evidence suggesting that the inquiry was based on anything more than rumor.

“Really? Is that what they’re saying?” Sanders shot back, heatedly.

“Based on what did they say that? Based on David Brock’s long history of honesty and integrity? The man who tried to destroy Anita Hill? Is this where this is coming from?” the 74-year-old bellowed.

Brock is a former conservative journalist who wrote a book criticizing Anita Hill, the woman who accused Supreme Court justice Clarence Thomas of sexual harassment. The political hit man has since converted to the Democratic party and is among Clinton’s most loyal supporters.

“Every one of you knows, you know it, that every day you’re being flooded by all of this negative stuff from the Secretary Clinton’s super PAC,” Sanders continued, adding that Hunt’s question is the first time he’s ever heard the rumor.

It is unclear if Brock is responsible for the rumor that Hunt seized on. But his group has been behind other anti-Sanders smears. In September, Correct the Record passed opposition research to reporters asserting that Sanders shared similarities with former Venezuelan president Hugo Chavez, a socialist, and with Jeremy Corbyn, the radical leftist who now heads the U.K’s Labour Party.

The assertion that Sanders is planning to manipulate the vote in Iowa is also reminiscent of Clinton campaign tactics during the 2008 Democratic primary. Back then, campaign staffers accused then-Illinois Sen. Barack Obama of the same nefarious strategy.

“I don’t want my integrity and honestly being impugned,” Sanders said Thursday. “I have no idea who says this. This is a lie, an absolute lie. We will win or we’ll lose, we’ll do it honestly.”

“I really dislike people suggesting, what, that we’re going to bring in students from out of state who are going to perjure themselves by saying they live in Iowa? Is that what they’re saying?”

“You talk about negative stuff, this is what, you know.”

[dcquiz] The irony is that it is Hillary Clinton who has accused Sanders of “going negative” against her in campaign ads and rhetoric. The former first lady said during an interview on Wednesday that Sanders had made a “low blow” against her by invoking former Vice President Dick Cheney when criticizing her vote in favor of the Iraq War. She has also criticized Sanders for implying that speaking fees she’s received from Wall Street banks have compromised her.

But Sanders points to Brock’s close relationship with the Clinton campaign as evidence of their negative bent.

“Why you bring people like David Brock into your campaign and Super PAC, I don’t know,” Sanders said. “But if this is the kind of stuff that they’re planning, that’s negative stuff.”

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