(CBS) This story was written by CBSNews.com political reporter Brian Montopoli.
In the Super Tuesday battle for GOP delegates, CBS News estimates that John McCain will win the delegate-rich, winner-take-all states of New York, New Jersey, Connecticut and Delaware, as well as the states of Illinois and Oklahoma.
CBS News also projects that Mike Huckabee will win Alabama and his home state of Arkansas. Earlier today, Huckabee won the West Virginia state GOP convention.
In addition, CBS News projects that Mitt Romney will take Massachusetts, where he served as governor, Utah, a winner-take-all state with a large Mormon population, and North Dakota.
So far today, McCain has won 242 delegates, Huckabee has won 48 delegates and Romney has won 45 delegates. Overall, McCain leads with 333 delegates, followed by Romney with 80 delegates and Huckabee with 55 delegates.
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As polls closed in Georgia, CBS News estimated that McCain, Romney and Huckabee were locked in a close, three-way contest.
According to early CBS News national exit polls, 40 percent of Republicans cited the economy as their most important issue today, followed by illegal immigration (22 percent), the war in Iraq (20 percent) and terrorism (15 percent). Sixty-one percent of Republican respondents said they had a negative view of the U.S. economy.
When asked for the most important quality in a candidate, 47 percent of GOP voters said it was that they share their values. Experience was cited by 24 percent of respondents, followed by saying what he believes at 21 percent and the ability to win at 7 percent.
Twenty-one states are holding Republican contests on Tuesday. Many are winner-take-all contests, in which the winner of the statewide vote is awarded the vast majority of the available delegates. That means today's results could provide some clarity in a race that has so far been notable for its uncertainty. (For coverage of the Democratic race, click here.)
Both Huckabee and Romney vowed to remain in the race tonight.
"We're going to keep on battling - we're going to go all the way to the convention, we're going to win this thing and we're going to go to the White House," Romney said.
Huckabee, who has complained that Romney has cast the Republican contest as a two-man race between him and McCain, told CBS News anchor Katie Couric " I think we're proving tonight that we're a choice for many, many conservatives, certainly across the south."
"Maybe Mitt Romney was right - it is a two-man race," he added. "It's just I'm the other man in the race."
Huckabee secured the day's first victory, having received 52 percent of the votes cast at the West Virginia state GOP convention. He took 18 of the state's Republican delegates.
According to CBS News chief political consultant Marc Ambinder, McCain called many of his representatives in West Virginia and asked them to vote for Huckabee. His goal was to thwart Romney, the man many political observers believe is McCain's biggest threat today. Huckabee's win is a blow to the former Massachusetts governor, who felt he had a solid shot at winning West Virginia and visited the state convention this morning. Romney blamed his loss on Huckabee, reported CBS Evening News Correspondent Bill Whitaker.
In Georgia, according to CBS News early exit polls, the most important quality for voters was that a candidate shares their values - and those voters are supporting Huckabee. Romney is seen as most able to manage economy, while McCain is seen as most qualified to be commander in chief.
Romney is hoping that he can garner enough delegates in Tuesday's Republican contests to keep his bid viable. He has focused on delegate-rich California, where pre-Super Tuesday polls showed him competitive with McCain, and states like Colorado, Montana, and North Dakota, where caucuses or conventions are held. Romney, a Mormon, also led in Utah, a largely Mormon state. (Full delegate count.)
"I'd like as many delegates as I can get," Romney told CBS News' The Early Show. "I think what began to happen in California over the weekend was really encouraging. I think you had a lot of conservative voices on talk radio and print voices saying, 'We've got to have a conservative, and Mitt Romney's the guy.'"
In recent days McCain has looked to shore up support in the South by stressing his pro-life record and sought to hold off Romney's challenge in California.
"Well, I'm sure we'll do very well throughout the country, and California will be tough, but I'm hopeful," McCain told The Early Show. "I'm happy with where we are."
"We're going to win today, and we're going to win the nomination, and we're going to win the presidency," McCain said today.
McCain, who had lobbed repeated criticisms at Romney while the pair were fighting to be crowned GOP frontrunner, had eased up on his rival following his wins in Florida and South Carolina.
But all that changed in the past 48 hours, as the candidates unleashed dueling negative ads and engaged in a public spat spurred by a letter that former GOP presidential nominee Bob Dole sent to Rush Limbaugh, a fierce McCain critic, asking him to give the Arizona senator a second look. (For details, see CBS News blog Horserace.)
McCain has been offering the rhetoric typical of a candidate who already has his party's nomination in hand, suggesting that "the first thing we've got to do after Tuesday is unite this party." It's an admission that while he feels confident that he will be the Republican nominee, he has yet to win over skeptical conservatives who are resistant to his candidacy.
Romney has looked to exploit that skepticism, casting himself as the true conservative in the field. He began advertising on Limbaugh's radio program and has been campaigning with McCain detractor and former senator Rick Santorum.
Romney has also been casting McCain as the ideological equal of Democrats Barack Obama and Hillary Clinton on certain issues. It's a criticism he echoed in his new ad, which links McCain and Clinton on “amnesty for illegal immigrants,” opposing the Bush tax cuts, a gas tax, and blocking conservative judges.
“I was impressed that yesterday Barack Obama said that Sen. McCain's position on illegal immigration was virtually indistinguishable from his,” Romney said Sunday. “I think it does make sense to have a candidate representing our party whose positions are distinctly different from the Democratic potential nominees. Mine are, and I'm proud of that.”
Huckabee, meanwhile, has also been engaged in a war of words with Romney, who suggested last week that "a vote for Mike Huckabee is a vote for John McCain." Huckabee called such rhetoric "voter suppression."
But many political observers say Huckabee's continued presence in the race has made it harder for Romney to close the gap on McCain, particularly in the south.
"As long as Huckabee stays in...he is taking votes away from Mitt Romney," said CBS News Chief Washington Correspondent Bob Schieffer.
Though McCain's campaign seemed moribund this past summer, the senator recovered to win primaries in New Hampshire, South Carolina and Florida. Romney, who has invested millions of dollars of his own money into his bid, won some early contests, including in his home-state of Michigan, but he has been unable to secure a breakthrough victory.
Huckabee, the Baptist minister who vaulted to the top-tier thanks to his appeal to social conservatives, has until today not been able to duplicate his early win in the Iowa caucuses. Rudy Giuliani, who led national polls for most of last year, and Fred Thompson, who was seen as a potential savior by Republicans disenchanted with their choices, both dropped out of the GOP race after disappointing results in early states.
Ron Paul, the libertarian-leaning Texas representative who has developed a small but passionate base of support, is looking to pick up delegates in states like Alaska today, but is not expected to be a significant factor.