Republican voters in South Carolina are casting ballots in the party's presidential primary. In Greenville, VOA's Brian Wagner reports the outcome may signal a clear lead among the field's top three candidates.

After early primaries and caucuses in the Republican race for the presidential nomination, no clear leader has emerged from the field of candidates.

Senator John McCain, former Arkansas Governor Mike Huckabee, and former Massachusetts Governor Mitt Romney have each claimed at least one victory so far. A win in South Carolina could provide needed momentum in upcoming primaries.

McCain has emphasized his military experience during the campaign in South Carolina, home to many active and retired military personnel.

At a campaign stop Friday, the Arizona senator addressed fears of an economic recession, saying what he called "out of control" government spending is part of the problem.

"Stop the spending. If we don't stop the spending, it is all going to go out the door," he said.

Huckabee, a Baptist minister, is expected to win support among the state's many Christian voters.

In his campaign, he appealed to religious opposition to gay marriage, saying, if elected, he would lead efforts to amend the constitution to define marriage as between a man and a woman.

"The fundamental unit of any government is family and strong marriages, and without that the rest of society begins to fall apart," he said.

Mitt Romney campaigned briefly this week in South Carolina before flying to Nevada for the Republican caucus there.

Former Senator Fred Thompson has been trailing the leading candidates so far, but hopes to make a strong showing in South Carolina, which is next to his home state of Tennessee.

Thompson has tried to separate himself from the other candidates by claiming he has the toughest policies to fight illegal immigration. During a rally on Friday, he told supporters that controlling immigration is a key component of national security.

"Part of that national security issue involves our own borders," he said. "A nation that cannot secure its own borders will not remain a sovereign nation, and we need to understand that."

The South Carolina vote may be crucial in the selection of the Republican candidate for the November election. Since 1980, no Republican has gone to the White House without winning the state's primary.

South Carolina Democrats hold their primary next Saturday.