Sanders, 81, had told Stephen Colbert of CBS’s “Late Show” Monday that Haley’s plan for mandatory tests of the mental acuity of politicians over the age of 75 was “nothing more than old-fashioned ageism” and “not acceptable.”

Haley, answering a final question from an audience member here at a campaign event, said: “Bernie Sanders lost his mind because I asked for that. He is exactly the reason we need it.”