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Story highlights

"Dr. Song's comment was inappropriate and insensitive," Sanders tweeted

Song made the remark at a Sanders rally in Washington Park Wednesday

(CNN) —  

Vermont Sen. Bernie Sanders said Thursday a supporter’s use of the phrase “corporate Democratic whores” ahead of his speech at a campaign rally in New York City’s Washington Square Park was “inappropriate and insensitive.”

Dr. Paul Song, railing against the relationship between politicians and corporations before Sanders’ supporters on Wednesday, 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.”

A law enforcement official estimated the crowd size at 15,000, though the campaign cited a a higher number of attendees – 27,000, according to a press release.

Some critics thought it was a swipe at Sanders’ rival for the Democratic presidential nomination, Hillary Clinton.

RELATED: Sanders rally fills NYC’s Washington Square Park

Song, a health care activist, tweeted later Wednesday that he was referring to some members of Congress.

“I am very sorry for using the term “whore” to refer to some in congress who are beholden to corporations and not us. It was insensitive,” he tweeted.

The comment drew criticism from Clinton supporters and others, who called on him to disavow it.

“Very distressing language to say the least. @BernieSanders should disavow,” Jennifer Palmieri, Clinton’s communications director tweeted.

Jane Sanders, the senator’s wife, told CNN’s Chris Cuomo Thursday that she did not hear the phrase but guessed it wasn’t about Clinton.

“I’m sorry, I didn’t hear it at all. Strange choice of words. I can’t imagine that anybody was speaking about Secretary Clinton that way. I don’t know who said that,” she said on “New Day.” “All the campaigns really need to take some responsibility for what surrogates say.”

Sanders himself weighed in via Twitter.

“Dr. Song’s comment was inappropriate and insensitive. There’s no room for language like that in our political discourse,” Sanders tweeted Thursday.

Thursday afternoon, Courage Campaign, a California-based progressive group that Song chairs, distanced itself from his remarks in a statement.

“Courage Campaign does not endorse political candidates. Dr. Paul Song, acting in his own capacity as a health care advocate, and separate from Courage Campaign, made comments at a rally in New York for Senator Bernie Sanders last night that are contrary to the values of Courage Campaign,” the statement said. “These comments were unacceptable and that sort of rhetoric has no place in our political dialogue.”

Song’s wife is Lisa Ling, host of CNN’s “This is LIfe with Lisa Ling.” In his speech, he also said positive things about President Bill Clinton, who helped secure the release of Ling’s sister from North Korea after she was captured in 2009.

CNN’s Shimon Prokupecz contributed to this report.