"The first thing is not to raise taxes," said former Arkansas Gov. Mike Huckabee. "Cut the marginal tax rate, if anything, and eventually go to a fair tax," he added, referring to his plan for a national sales tax to replace the income tax.
Arizona Sen. John McCain stressed spending cuts to get the budget deficit under control, although he also said it was important not to let Bush administration-era tax cuts expire. He pledged to "wield the veto pen" and block all pork barrel spending bills that Congress sends him.
While the debate was held in South Carolina, the Michigan primary will be held first, a contest in which Romney, Huckabee and McCain are the principal antagonists. It's unlikely all of them can survive a defeat there, particularly a third-place finish.
South Carolina's primary is scheduled for Jan. 19, and has drawn a different group of competitors. Former Sen. Fred Thompson of Tennessee has made it clear he needs a victory or something close to it, while McCain and Huckabee also are counting on a strong showing. Romney abruptly canceled television advertising in the state earlier this week, and is concentrating for the moment on Michigan.
Thompson underscored the urgency of a strong South Carolina showing when he launched an attack on Huckabee, standing a few feet away on the debate stage.
"This is a battle for the heart and soul of the Republican Party and its future. On the one hand you have the Reagan Revolution ... on the other hand you have the direction that Governor Huckabee would take us ... liberal economic policies, liberal foreign policies," he said.
Huckabee seemed unruffled. "The Air Force has a saying that if you're not catching flak you're not over the target. I'm catching the flak. I must be over the target," he said. He added he had cut taxes as governor of Arkansas and was re-elected by his constituents, a sure sign, he added, that they were pleased with his performance.
Asked about last weekend's Persian Gulf incident in which Iranian speed boats harassed U.S. warships, none of the presidential rivals found fault with U.S. naval commanders on the scene.
But several took the opportunity to stress their determination to take stronger steps against Iran in the future. "I think one more step, you know, and they would have been introduced to those virgins that they're looking forward to seeing," said Thompson.
Huckabee said if it happened again, the Iranians "should be prepared to see the gates of Hell."
McCain, the only candidate with experience in the Navy, refused to second guess the actions of the commander of all the battle groups.
"I believe Iran represents a very serious threat," said Romney. He added he believes the incident was a calculated one to test U.S. defensive responses and was a "diversionary action ... It points out that we have in Iran a very troubled nation," he added.
Romney drew scattered boos and applause from the audience when he criticized Paul for saying the United States must avoid another war.
Romney said Paul had been reading "too many press releases by (Mahmoud) Ahmadinejad" the Iranian president. "Make fun buddy," muttered a clearly irritated Paul.
Thompson, who advocates a cut in corporate taxes, also said "we need to count on the Federal Reserve doing the right thing on interest rates" to keep the economy from tumbling into recession. He also said tax cuts enacted in recent years should be extended.
Former New York Mayor Rudy Giuliani also advocated tax cuts, and his campaign purchased an advertisement during the first commercial break that said he would send the largest tax cut in history to Congress on his first day in the White House.
Alone of the six presidential rivals on the debate stage, Paul said, "I believe we are in a recession. I believe it's going to get a lot worse."
The first three contests of the Republican campaign have yielded three different winners: Huckabee, first in the leadoff Iowa caucuses; Romney, victor in the little-contested Wyoming caucuses, and McCain, triumphant in last Tuesday's fiercely fought New Hampshire primary.
The debate unfolded as one poll showed McCain getting a bounce from his New Hampshire triumph and moving narrowly ahead of Huckabee and Romney in South Carolina.
That state's GOP Chairman, Katon Dawson, fiercely sought to protect South Carolina's first-in-the-South primary status, and maneuvered to force candidates to pay attention to the state by scheduling a debate they seemingly couldn't ignore.
By midday, the area around the Myrtle Beach Convention Center had turned into a political carnival. The six Republicans were greeted by giant sand sculptures of their heads - a Mount Rushmore-like rendering of the big names in the 2008 GOP race.
Their campaign buses, with their competing slogans, were parked in a nearby lot. One of Thompson's said, "Restore Law & Order to the White House" - a play on the TV show that made him a household name.
The debate was sponsored by the South Carolina Republican Party and Fox News Channel.