Maybe he should ask the FBI for a clue?
“People familiar with the process said Ms. Palin had responded to a standard form with more than 70 questions. Although The Washington Post quoted advisers to Mr. McCain on Sunday as saying Ms. Palin had been subjected to an F.B.I. background check, an F.B.I. official said Monday the bureau did not vet potential candidates and had not known of her selection until it was made public.”