An aide to Democratic presidential candidate Bernie Sanders Bernie SandersMcConnell accuses Democrats of sowing division by 'downplaying progress' on election security The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters Why Democrats must confront extreme left wing incitement to violence MORE said Thursday evening that rival Hillary Clinton Hillary Diane Rodham ClintonHillicon Valley: FBI chief says Russia is trying to interfere in election to undermine Biden | Treasury Dept. sanctions Iranian government-backed hackers The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters FBI chief says Russia is trying to interfere in election to undermine Biden MORE "should be ashamed" of her association with longtime ally David Brock.

Brock, who heads several groups supporting Clinton's bid, slammed a new ad from Sanders on Thursday and accused the Vermont senator of not caring about black people.

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Sanders spokesman Michael Briggs issued a scathing statement directed at Brock's comments and stressed that Sanders has "one of the strongest civil rights records in Congress."

"He doesn’t need lectures on civil rights and racial issues from David Brock, the head of a Hillary Clinton super PAC," Briggs said in the statement.

"Twenty-five years ago it was Brock — a mud-slinging, right-wing extremist — who tried to destroy Anita Hill, a distinguished African-American law professor," the Sanders spokesman continued, referring to Brock in 2001 disavowing a book he had written attacking the woman who accused Clarence Thomas of sexual harassment.

"He later was forced to apologize for his lies about her. Today, he is lying about Sen. Sanders," Briggs said.

Briggs slammed Clinton for hiring "a mudslinger like David Brock," adding: "She should be ashamed of her association with Brock."

Brock had remarked to The Associated Press earlier in the day that a new Sanders ad depicting overwhelmingly white supporters was a "significant slight to the Democratic base."

"From this ad it seems black lives don't matter much to Bernie Sanders," Brock told the AP of the ad, which optimistically showed large crowds applauding Sanders to the tune of Simon and Garfunkel's "America."

Clinton is seeking to fend off an upset by Sanders in the early-voting states of Iowa and New Hampshire, where ballots will be cast in early February and polls indicate a close race.