Well, Trump has not been in DC so it cant be him. But if the list is released, then that will be pinned on him.
Cruz was in Texas so that leaves Kasich (he had left Congress but I can't confirm that he had left DC), Bill & Hillary, Huma, Mr. Huma, Obama, Creepy Uncle Joe Biden and Bernie as suspects.
Was Rubio even out of High School? There might be a Republican or two on the list but the remaining contenders probably aren't. (Unless their manhood is long enough to reach across state lines.)