WASHINGTON (AP) -- It's the busiest day of the Republican race for president, but this Super Tuesday probably won't settle much.
One-third of the delegates needed to win will be doled out in voting across 10 states -- slimmed down to half its 2008 size. But because delegates are handed out by share, it's not likely to end the GOP race.
Sure, Super Tuesday could nudge Newt Gingrich out of the race, or lend Ron Paul more credibility. But it won't be easy for either Mitt Romney or Rick Santorum to score a decisive advantage. A close second in a state can pay off almost as well as first place.
Win some big states, especially Ohio, and the symbolism is powerful, of course.
Romney might cement the front-runner status that keeps slipping through his fingers. Santorum could prove he's the real thing.
What's at stake, what's it mean and what might happen when states stretching from Alaska to Virginia vote on the same day? A Super Tuesday tip sheet:
Delegates for grabs Tuesday: 419.
Delegates already won: 353. Romney, 203; Santorum, 92; Gingrich, 33; Paul, 25.
Delegates needed for the nomination: 1,144.
Super Tuesday is super expensive:
This one day of voting can eat up millions of dollars in TV advertising. When it comes to commercials, Romney and his campaign's supporters have outgunned the rest of the field.
Restore Our Future, a political action committee that backs Romney, had spent about $5.5 million in Super Tuesday states by the end of last week, according to data The Associated Press obtained from media buyers.
It's all about Ohio:
It's the race to watch. Political junkies get all misty-eyed over this Rust Belt swing state, and not just because of its 63 delegates.
No Republican nominee has ever become president without winning Ohio in the general election. That makes it a powerful proving ground for the men trying to show they can take on President Barack Obama.
It's home to Joe the Plumber and tens of thousands of auto workers, but Ohio's not all blue-collar. It's also home of the Rock and Roll Hall of Fame, high-tech science, medical and energy workers, suburbanites, soybean farmers and a quarter-million dairy cows (OK, the cows can't vote). The big issue is the economy, including Obama's bailout of the auto industry.
Santorum and Romney are duking it out in the state. Look for the outcome to generate more buzz than any other Super Tuesday contest.
Newt's last stand or Gingrich rises again?
Get out the hook for Newt Gingrich if he loses in Georgia, the state he represented in the U.S. House for two decades.
Gingrich hopes to win decisively here and pick up enough other delegates to relaunch his up-and-down campaign, which has been mostly down-and-out since he lost Florida in January. He's got endorsements from Gov. Nathan Deal and Herman Cain, a fellow Georgian. He's got a new pitch, claiming he can bring down the cost of gas to $2.50 per gallon.
Santorum is pushing hard to wrest the state's Christian conservative and tea party voters away from Gingrich. Romney remains a force, even if the state is outside his comfort zone. Georgia boasts the day's biggest cache of delegates: 76.
Elsewhere in the South:
Two other Bible Belt states, Tennessee and Oklahoma, are central to Gingrich's hopes of revival. But Santorum insists he'll be the big story in both.
In Tennessee, a confident-sounding Santorum is trying to walk the footsteps of another outspoken Christian conservative, Mike Huckabee, who won this primary four years ago. Romney boasts the support of popular Gov. Bill Haslam, while Gingrich is getting plugs from one of the state's most colorful political figures: former senator, movie actor and "Law & Order" star Fred Thompson. At stake are 55 delegates.
Dotted with drilling rigs and cattle ranches, Oklahoma straddles the South and the Great Plains and sits squarely among the reddest of the red states. Santorum tagged it "ground zero of the conservative movement," and his anti-abortion, pro-family values message attracts enthusiastic crowds here. The other three hopefuls also have dropped in, hoping to prove their conservative bona fides to the Okies. It offers 40 delegates.
Paul's big night?
The anti-war, libertarian-leaning, unorthodox Republican hasn't won a single state. Super Tuesday could change that.
Paul is focusing on the three caucus states -- Idaho, North Dakota and Alaska -- where a big turnout by his cadre of enthusiastic followers would have the most impact. Even if he doesn't score a win, he's likely to pick up delegates to help power him into this summer's Republican convention with enough clout to promote his ideas.
But his rivals won't make it easy.
Idaho's big Mormon population -- about a fourth of its voters -- bodes well for Romney, who is Mormon. Santorum's looking to win in North Dakota, and Romney's trying, too.
Paul, a Texas congressman, may be the only one to journey to Alaska, however; he was there on Sunday. Meanwhile, Alaska's most famous Republican, Sarah Palin, has been saying some nice things about Gingrich.
Together, the three caucuses pay out 84 delegates (Idaho 32, North Dakota 28, Alaska 24).
What's the deal with Virginia?
Gingrich would love to compete in this Southern state, but he's not. Only Romney and Paul landed spots on the ballot, by having early organizations strong enough to collect the required 10,000 signatures. That leaves Virginia mostly a curiosity. What kind of showing can Paul muster going mano-a-mano with Romney? The fight is over 46 delegates.
There's little drama in the Northeastern races. Romney's virtually unopposed in his power base of Massachusetts, where he was governor just over five years ago. Delegates: 38. He's expected to win neighboring Vermont handily, too, although Santorum seeks to peel away some of its 17 delegates.
Wyoming is almost a Super Tuesday state. Some of its counties start picking delegates Tuesday. But others won't caucus until Saturday, so no official statewide results before then. Romney won a nonbinding straw poll in Wyoming last month with Santorum close at his heels. At stake: 12 delegates.
Caucuses and primaries in Kansas, Alabama, Hawaii, Mississippi, Missouri, Illinois and Louisiana fill out the busiest month of the nomination season. Three territories -- American Samoa, the Virgin Islands and Puerto Rico -- also get their say in March.
Associated Press writer Jack Gillum contributed to this report.