The polls are open in Georgia as voters get the chance to pick nominees for the state’s top offices and settle a bruising fight for an open Senate seat that could determine congressional control.

The race to replace retiring U.S. Sen. Saxby Chambliss has attracted national attention as five high-profile GOP candidates are locked in a vicious battle for their party's nod. Democrat Michelle Nunn is competing for her party's nomination for the seat, but first she must defeat three lesser-known challengers.

Republicans need to flip six seats to regain control of the U.S. Senate, and losing the GOP-held spot in Georgia would be a crushing blow. That's one reason why the race in Georgia has already spawned more than $9 million in TV ads and millions more in outside spending.

Polls suggest that former Georgia Secretary of State Karen Handel, U.S. Rep. Jack Kingston and ex-Fortune 500 executive David Perdue are in a race for the top two spots in a July 22 runoff. But forecasts of light turnout could give U.S. Reps. Paul Broun and Phil Gingrey an opening. Two other Republicans are also in the running.

Republican Gov. Nathan Deal faces two GOP challengers in his quest for a second term. Former Dalton Mayor David Pennington vows to be a more conservative option, while Superintendent John Barge says he would bring a renewed focus on education. Deal has made few campaign promises but said his record of job growth speaks for itself.

Tuesday's victor faces Democrat Jason Carter, a state senator from Atlanta who is a grandson of former President Jimmy Carter. The younger Carter, who has tapped his grandfather's lucrative donor network, is running as a moderate. Libertarian Andrew Hunt, a technology executive, is also in the running.

Three open House seats are up for grabs, and several others are contested. Former Rep. Bob Barr is a top contender to replace Gingrey in a northwest Atlanta district, but he must survive a crowded field that includes former state Sen. Barry Loudermilk, state Rep. Ed Lindsey and entrepreneur Tricia Pridemore.

Rep. Hank Johnson, a DeKalb County Democrat, faces a challenge from DeKalb Sheriff Tom Brown. Six GOP candidates have lined up to succeed Kingston in southeast Georgia, and seven Republicans are in the hunt to replace Broun in the northeast. Five GOP hopefuls are also fighting to challenge Democratic Rep. John Barrow of Augusta.

One of the most hotly contested races is for the open state schools superintendent seat. Nine Republicans are jockeying for a spot in a runoff in a race that features former Hall Commissioner Ashley Bell, administrator Mike Buck and businessman Fitz Johnson. On the Democratic side, state Rep. Alisha Thomas Morgan and Decatur school board member Valarie Wilson are among the top contenders.

Scores of down-ticket races will be decided by Tuesday's contest as well. House Speaker David Ralston drew a tea party challenger, and state Sen. Don Balfour, recently exonerated on fraud charges, faces two rivals. Dozens of other legislative seats are also in play, though the GOP will still control both chambers regardless.

One of the most intriguing races involves the comeback bid by former DeKalb County CEO Vernon Jones, who is running for county sheriff against five opponents who each have law enforcement experience.

The polls opened at 7 a.m. and close at 7 p.m. You can check out a comprehensive list of all the candidates and analyze their stances on key issues in the AJC voting guide. You can also review some of the key factors that will decide today's race. And stay tuned on ajc.com and myajc.com throughout the day for all the latest election details.