John McCain holds a comfortable lead in the contentious Arizona Republican Senate primary, according to the most recent public polling, making him the strong favorite against former Rep. J.D. Hayworth on Tuesday. But it’s been a costly road to a fifth term for the 2008 GOP presidential nominee, and the experience is likely to leave a lasting and unsightly stain on his legacy. It’s not just the $20 million he’s spent already this election or the scorched earth campaign that he’s run. Rather, it’s the choices he’s made and the positions he’s embraced — and what it reveals about him...