Story highlights Castro violated the Hatch Act in an interview with Katie Couric, official says

Castro was touting Clinton's presidential campaign

(CNN) Housing and Urban Development Secretary Julian Castro violated a federal law against mixing official business with politics when he touted Hillary Clinton in an April interview with Yahoo's Katie Couric, the Office of Special Counsel said Monday.

Castro is a top surrogate for Clinton's presidential campaign and -- while not expected to be the choice -- is often mentioned on lists of vice presidential prospects.

He violated the Hatch Act, which prohibits federal workers acting in their official capacity from attempting to influence elections. In the Couric interview, he appeared with the official HUD seal, was introduced as the secretary and spent the first seven minutes focused on HUD programs before Couric turned to Clinton.

The Office of Special Counsel wrote : "Although he stated during the interview that he was 'taking off my HUD hat for a second and just speaking individually,' to indicate he was answering questions in his personal capacity, that disclaimer could not negate the fact that he was appearing in his official capacity for the rest of the interview, as the official HUD seal remained behind him and his political comments were bracketed by statements concerning official HUD policies and programs."

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