President George Albert Smith offers a prayer for the U.S. Senate, and the 'Congressional Record' publishes his invocation's full text. Nineteen years later, 20 May 1966, first counselor Hugh B. Brown does likewise. In 1974 Apostle (later LDS president) Gordon B. Hinckley opens the U.S. House with prayer; Pres. Spencer W. Kimball prays in the Senate.
[Source: The Mormon Hierarchy - Extensions of Power by D. Michael Quinn, [New Mormon History database (http://bit.ly/NMHdatabase)]]