Amid largely trouble-free elections so far this primary season, at least one campaign is worried about serious troubles in Arizona, where voters today are casting their ballots. John McCain is likely to score a big win on the GOP side, but among Democrats, the race is a fierce battle between Hillary Clinton and Barack Obama.

Clinton leads by 6 points in the latest RCP Arizona Average, but Obama has support from Rep. Raul Grijalva and Governor Janet Napolitano, giving him an organization on which to rely.

Clinton's camp, though, says funny business is going on at polling places around the state. Polling place locations have been changed and some names are missing from voter rolls. The Clinton camp just released a statement reminding voters they can cast provisional ballots. If problems are widespread, Obama's vote total could be affected as well, putting a new spotlight on what is already a closely watched barometer.

Still, it has been remarkable that the two biggest voting problems -- running out of appropriate stickers at some Democratic caucuses in Iowa and temporary shortages of ballots in New Hampshire -- have been relatively minor. Voting reforms must have come a long way since debacles in Florida and Washington State in recent years. A good sign of things to come for November?