In a speech to class 2016 of Rutgers University Obama makes a case for professional politicians. He also does not distinguish between the executive and representative politicians, unfortunately. We can savely assume he meant the executive.
(…) it’s interesting that if we get sick, we actually want to make sure the doctors have gone to medical school, they know what they’re talking about. (Applause.) If we get on a plane, we say we really want a pilot to be able to pilot the plane. (Laughter.) And yet, in our public lives, we certainly think, “I don’t want somebody who’s done it before.”
Read the whole speech at whitehouse.gov.