The 2012 presidential election may be 29 months away, but the potential players are stalking each other like chess grandmasters. Tonight's round of gubernatorial and Senate primaries could provide early indicators of who is most shrewdly mobilizing their pieces into position. Three states with big races on Tuesday represent potential game-changers in 2012. Iowa and South Carolina occupy key early positions in the presidential-primary calendar, while California boasts a mother lode of winner-take-all delegates. For presumed hopefuls like Mitt Romney, Sarah Palin, and Mike Huckabee, the calculation is simple. Endorse a statewide candidate who wins (both tonight and in November's...