Who is the choice of rank-and-file Republicans for vice president? A third of them don’t have a clue about whom John McCain should pick, but more mentioned our man Mike Huckabee than anyone else. A Gallup Poll asked Republicans and Republican-leaning independents to say whom they would like to see McCain tap, and 18 percent named Huckabee. Mitt Romney was second with 15 percent but no one else was in double digits.  Thirty-six percent had no opinion or could not name anyone. Democrats John Edwards and Bill Richardson weighed in at 1 percent each, same as Newt Gingrich.