Rachel Mitchell, an Arizona prosecutor specializing in sex crimes, questioned Christine Blasey Ford, Judge Brett M. Kavanaugh’s first accuser, on Thursday on behalf of the Republicans on the Senate Judiciary Committee.

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The move allowed the 11 Republicans on the committee — all white men — to avoid the image on national television of them grilling Dr. Blasey in a hearing about the sexual assault she has accused Judge Kavanaugh of carrying out in high school. Senator Mitch McConnell of Kentucky, the majority leader, referred to Ms. Mitchell as a “female assistant,” a description criticized by some as sexist and disrespectful to women.

Dr. Blasey had sought to have the senators question her instead of a lawyer.

In announcing the selection of Ms. Mitchell, the chairman of the Judiciary Committee, Senator Charles E. Grassley, called her a “career prosecutor with decades of experience prosecuting sex crimes.”

“I’m very appreciative that Rachel Mitchell has stepped forward to serve in this important and serious role,” Mr. Grassley, Republican of Iowa, said. “Ms. Mitchell has been recognized in the legal community for her experience and objectivity.”