David O. McKay received a twelve-page letter from John Birch Society president Robert Welch, "a cursory glance of which indicates or pleads for permission for Ezra Taft Benson to serve on the National Council of the Society." In his conclusion, Welch indicated that Benson had already agreed to serve on the council, subject only to McKay's consent.
"It was agreed that Elder Benson would answer Mr. Welch and tell him that it would be impossible for him to serve on the Council at this time."
[Source: David O. McKay diary, ; Robert Welch to David O. McKay, February 21, 1967; David O. McKay diary, March 22, 1967 as referenced in Gregory A. Prince and Wm. Robert Write, David O. McKay and the Rise of Modern Mormonism. Salt Lake City: University of Utah Press (2005)]