Bernie Sanders criticized a surrogate on Thursday morning for using charged language at a rally in Washington Square Park in Manhattan the night before.

Speaking in front of a crowd of some 27,000 people, according to campaign estimates, healthcare activist Dr. Paul Song said, “Medicare-for-all will never happen if we continue to elect corporate Democratic whores who are beholden to big pharma and the private insurance industry instead of us.”

Sanders was not at the Washington Square Park rally at the time that Song spoke, and arrived later to deliver his marquee speech. But he was quick on Thursday morning to disavow Song’s use of the word “whore.”

Song also apologized shortly after his speech, saying he was referring to “some in Congress” but not Hillary Clinton. The comment quickly rocketed to the top of Twitter’s trending list, under the hashtag #DemocraticWhores.

Sanders’ surrogates have sometimes strayed off-script and gotten the Vermont senator in hot water. In February, ally Killer Mike said at a pro-Sanders rally “having a uterus doesn’t qualify you to be president,” prompting a backlash among women and Clinton supporters.

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