NEW YORK—Outgoing Mayor Michael Bloomberg finally broke his silence on the campaign to succeed him, saying in an interview published Saturday that he believes Democratic mayoral frontrunner Bill de Blasio has run a “racist” campaign based on “class warfare.”

In an interview with New York Magazine published just days before the Sept. 10 mayoral primary, Bloomberg tore into de Blasio, the city’s public advocate, accusing him of playing up his multiracial family to win support.

“I mean he’s making an appeal using his family to gain support. I think it’s pretty obvious to anyone watching what he’s been doing,” Bloomberg said. “I do not think he himself is racist. It’s comparable to me pointing out that I am Jewish in attracting the Jewish vote. You tailor messages to your audiences and address issues you think your audience cares about.”

De Blasio, an Italian American, campaigns almost daily with his wife, Chirlane McCray, who is black. Their kids—Chiara, 18, and Dante, 15—have been equally prominent players in his campaign. Last month, Dante de Blasio was featured in two television ads highlighting his father’s opposition to the city’s controversial “stop and frisk” measure that allows police officers to randomly search people.

At a campaign stop on Saturday, de Blasio rejected Bloomberg’s comments.

“It’s obviously inappropriate, and I am surprised to hear him say it,” de Blasio said, according to the New York Daily News . “I think people feel something good about this family so I don’t understand what the mayor is saying.”

His rivals—former Comptroller Bill Thompson and City Council Speaker Christine Quinn—also defended de Blasio and his family, both calling the mayor’s comments inappropriate.

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