Herman Cain crooning to the National Press Club audience Monday. (Pablo Martinez Monsivais/AP)

C-SPAN viewers may have been stunned when the GOP candidate burst into song at the end of his National Press Club speech Monday, but Cain has incorporated a cappella into many of his campaign stops. He charmed a fairground crowd with the same hymn (“He Looked Beyond My Fault,” set to the melody of “Danny Boy”) at a speech in Waverly, Tenn., a couple weeks ago. When his sound system malfunctioned in Jackson, Tenn., he belted out “The Impossible Dream.” An Ames, Iowa, crowd was treated to another hymn, “I Must Tell Jesus.”

He’s got a history of this: The Omaha World-Herald recently exhumed video of the former Godfather’s CEO singing, to the John Lennon tune, “Imagine there’s no pizza . . .” at a 1991 party.

That vibrato! He must have had formal training, no? His rep didn’t get back to us with Cain’s musical credentials. But in his recent memoir, the candidate suggests his political success was ignited by his vocal talent. At Morehouse College, he was selected not only for the celebrated Glee Club but its ever more elite Quartet — of which he was elected president. “It was evident,” he wrote, “that other people perceived my leadership potential even before I did.”

Video: Herman Cain, “Imagine there’s no pizza. . .”

Video: Herman Cain sings in Ames

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Video: Herman Cain sings ‘God Bless America’ over 9/11 footage