Can South Carolina Crown McCain's Campaign?

A win in South Carolina today for John McCain could catapult his campaign to the front of the Republican pack.

"I think it's very important. Obviously every person who's won the South Carolina primary for I don't know how many years, has been the nominee of the [Republican] Party," the Arizona senator told ABC News' Ron Claiborne Friday.

With the polls now open, McCain is hoping his military credentials and fiscal conservatism will carry him to the lead.

"I have gotten more involvement in every national-security challenge for the last 20 years. I believe that I am more qualified to be commander in chief," he said.

Running on the Surge

In his final push for votes, the Vietnam vet has spent the week touting his early support for the troop surge in Iraq, in a state that's home to an estimated 400,000 veterans.

At a campaign event near Columbus, he read the crowd a headline from a newspaper as proof that the surge he backed had worked. "'Figures Show Dramatic Gains Since U.S. Build-Up," he read, to the applause of his audience.

Dirty Tricks

McCain has complained that he's again been the target of some nasty negative campaigning. One mailer — from "Vietnam Veterans Against McCain" — accuses him of collaborating with the enemy as a prisoner of war.

In his first fight for South Carolina, which McCain lost to George Bush in the 2000 primary, he faced a massive smear campaign that ultimately sank his presidential bid.

McCain says that this year the dirty campaign tricks are back, but not as bad.

"Yeah, we're seeing some of that, in the phone calls, and some of the stuff, fliers that are going around. But this time we have a strong political and financial base to try to respond to a lot of that," McCain told Claiborne.

Economic Woes

Economic worries have risen to the top of voter issues, but McCain stops short of saying the United States is headed for a recession.

"I think we're in for some tough times here. I don't think there's any doubt about that. It depends on what we do. If we will stop the excess spending, make the tax cuts permanent, um, make sure that we have a stable and, a fiscal situation that Americans can depend on. I think that our economy can recover."

Other Candidates

McCain's campaign has made headlines in recent weeks for its frequent sparring with the Romney campaign, but today McCain is hoping to stay above the fray.

"I have great respect for everybody that's running, and I know this is a tough business. I believe I am more experienced … I have great respect for all of them, but I believe that my credentials lend themselves to the support of the American people," he told Claiborne.

Former Arkansas Gov. Mike Huckabee trails McCain in the polls but has been gaining fast. The two are now practically tied.

Huckabee has largely ignored McCain though and instead has repeatedly attacked former Tennessee Sen. Fred Thompson.

The Thompson campaign could end with a poor showing in South Carolina, or get some badly needed life blood.

In response to recent heat, the former "Law & Order" star, who is now a hard-liner on immigration, has been attacking Huckabee for allowing the children of illegal immigrants in Arkansas to qualify for in-state college tuition.

Former Massachusetts Gov. Mitt Romney, winner of the Michigan primary this week, made little more than a token effort in South Carolina in the final weeks. He's now in Nevada, which is also holding its caucus today.

Though voters will be choosing from three winners and no clear front-runners today, today's results will likely be a kingmaker.