premise: In the '50s, he reworked It Ain't Necessarily So for Adlai Stevenson (and included the first sung reference to a vice-presidential  L'il Nixon was small, but oh, my/His office expenses were high) as well as Love Is Sweeping the Country (also from Of Thee I Sing ):
hypothesis: he reworked It Ain't Necessarily So for Adlai Stevenson