Former Pennsylvania Sen. Rick Santorum, left, speaks as former Massachusetts Gov. Mitt Romney listens at the South Carolina Republican presidential candidate debate in Myrtle Beach, S.C., Monday, Jan. 16, 2012. (Credit: Pool,AP Photo/Charles Dharapak)
MYRTLE BEACH, South Carolina (CNN) -- Mitt Romney's rivals put his corporate record under the microscope in a Republican presidential debate Monday, with most of his GOP opponents looking to dislodge the party's frontrunner from his perch ahead of South Carolina's primary on Saturday.
The issue of poverty also factored prominently into the Martin Luther King Jr. Day match-up where a large studio audience roared in support or disdain over candidates' stated positions.
Former House Speaker Newt Gingrich faced off with a debate moderator over remarks the candidate had made about the growing class of struggling Americans, as the GOP field worked to woo voters in a state where unemployment is pushing 10%.
The debate began with candidates launching a multifront offensive against Romney.
Gingrich defended his criticisms of Romney's career at private equity firm Bain Capital, saying he would not be "intimidated" by blowback from his own party.
"We need to satisfy the country that whoever we nominate has a record that can stand up to Barack Obama in a very effective way," Gingrich said.
Texas Gov. Rick Perry called on Romney to release his tax returns -- and, in a bid for a second look -- told the rowdy studio audience watching the debate that "we cannot fire our nominee in September." He said Republicans should carefully examine each candidate's record during the primary process.
"Mitt, we need for you to release your income tax so the people of this country can see how you made your money, and I think that's a fair thing," Perry said.
Asked directly about the issue, Romney appeared ruffled and said he has released information about his assets as required by law. He indicated he would likely release his tax returns in April -- though he refused to commit to doing so.
Former Sen. Rick Santorum also took aim at Romney, the winner of the Iowa caucuses and New Hampshire primary, over an attack ad from a political action committee supporting Romney.
Santorum called on Romney to publicly denounce the ads, and aggressively pressed him to answer questions about his stance as governor on whether felons could vote.
"We have plenty of time, I'll get there," Romney responded to Santorum. "I'll do it in the order I want to do."
Romney defended his records both as governor of Massachusetts and in the private sector, saying companies he helped invest in while leading Bain had eventually created 120,000 jobs.
"My record is out there," Romney said. "Proud of it."
The debate turned to race and poverty as moderator Juan Williams asked Gingrich a series of questions about the candidate's charge that Obama has been "the food stamp president" and a suggestion that poor adolescents do light janitorial work to earn money.
Taking the confrontational tone Gingrich has wielded to great political effect in previous forums, the candidate argued back and enlivened the audience by proclaiming: "Only the elites despise earning money."
He said his own daughter had done janitorial work as an adolescent.
"I believe every American of every background has been endowed by their creator with the right to pursue happiness," Gingrich said. "And if that makes liberals unhappy, I'm going to continue to find ways to help poor people learn how to get a job, learn how to get a better job and learn some day to own the job."
During a segment on foreign policy, Texas Rep. Ron Paul again stood alone as his rivals took hawkish positions on military spending and tracking down and punishing alleged terrorists.
As some in the large studio audience booed, Paul accused his opponents of "war-mongering" and urged Americans to adopt the "golden rule" regarding foreign policy.
"This country doesn't need another war, we need to quit the ones we're in!" Paul said.
Romney tacked in the opposite direction, criticizing Obama for drawing down troops in Iraq and declaring as president he would direct military leaders to track down terrorists.
"We go anywhere they are and we kill them," he said.