Former Secretary of State Hillary Clinton campaigned for Maryland Democratic gubernatorial candidate Anthony Brown (right) in October. President Obama and Michelle Obama have also campaigned in the state. This level of Democratic star power so late in the race is unusual in a reliably blue state. Patrick Semansky/AP hide caption

itoggle caption Patrick Semansky/AP

Alaska Gov. Sean Parnell was supposed to be cruising to re-election, but he's now in a serious contest against a non-partisan ticket. Mark Thiessen/AP hide caption

itoggle caption Mark Thiessen/AP

Democrat Charlie Crist, a former Republican governor of Florida (left), and Rick Scott, the current Republican governor of Florida, listen to the moderators during a gubernatorial debate on Friday. The two are facing off in a tight race that's fueling a barrage of negative campaign ads. Lynne Sladky/AP hide caption

itoggle caption Lynne Sladky/AP

Massachusetts Democratic gubernatorial candidate Martha Coakley celebrates with supporters as she claims victory in the primary election Tuesday in Boston. Elise Amendola/AP hide caption

itoggle caption Elise Amendola/AP

Rhode Island Democratic gubernatorial nominee Gina Raimondo waves as she takes the stage to address supporters during a primary election night watch party Tuesday in Pawtucket. Steven Senne/AP hide caption

itoggle caption Steven Senne/AP

Florida Gov. Rick Scott, who led state opposition to the federal Affordable Care Act, met with reporters in Tallahassee after the U.S. Supreme Court upheld the bulk of the law. Scott, a Republican, has made his opposition central to his re-election campaign. Steve Cannon/AP hide caption

itoggle caption Steve Cannon/AP