E M E R Y V I L L E, Calif., Feb. 13 — Lt. Gov. Cruz Bustamante used a racial slur during a Black History Month speech in what he called an embarrassing slip of the tongue.

Bustamante, a Hispanic Democrat who has focused on improving race relations, said he meant to use the word “Negro” but slipped and said the word “nigger” during his speech about the black union movement.

About one-fourth of the 400 people at the event Friday left in protest, said Marshall Walker, master of ceremonies.

“I was appalled he would even say it as a slip. You don’t make a slip like that unless it is something you say normally,” said Gwendalyn Bello, who attended the event, the Coalition of Black Trade Unionists’ annual awards dinner and scholarship fund-raiser.