The seeds of Walker’s withdrawal had been planted five nights earlier in Simi Valley, when Walker spoke for fewer minutes than any other candidate on the debate stage. Instead of a breakout performance, the closet thing he had to a signature moment came as Carly Fiorina finished her impassioned answer on Planned Parenthood. Walker lifted his finger, as if to interject. He wasn’t called upon. He would speak only once in the next 30 minutes.