David Brock, a longtime ally of the Clinton family, told the Associated Press on Thursday that Democratic presidential candidate Sen. Bernie Sanders’ (I-VT) latest TV ad showed a disregard for Democratic voters of color.

Brock told the AP that he thought Sanders’ new “America” ad, which uses Simon and Garfunkel’s song of the same name in lieu of spoken words, was focused on white voters. The ad shows Sanders greeting mostly white supporters on the campaign trail, with the crowds’ sizes slowly increasing.

Brock characterized the ad as 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.

Brock, formerly a conservative journalist, runs numerous super PACs supporting former Secretary of State Hillary Clinton’s presidential campaign.

The Sanders campaign fired back in a statement to the AP, saying Clinton should be “ashamed” of her association with Brock.

“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. He later was forced to apologize for his lies about her,” Sanders campaign spokesman Michael Briggs told the AP. “Today, he is lying about Sen. Sanders.”

Clinton leads Sanders nationally by a margin of 13.2 points, according to a Real Clear Politics average. The nominating contests start on Feb. 1 in Iowa.