FLORENCE, S.C. (AP) - Seeking to protect his standing here, Republican presidential front-runner Mitt Romney on Tuesday assailed challenger Rick Santorum's record on voting rights for felons, an issue that resonates strongly with conservatives. Santorum separately argued that the former Massachusetts governor "promotes lies" as the two intensified their dispute from the previous night's GOP debate.
"We have a candidate who's not going to stand up and tell the truth," Santorum told reporters in Charleston, complaining that Romney refuses to condemn TV ads run by his supporters. "That leads to real serious questions about whether that man can be trusted to tell the truth on a variety of things."
But Romney, speaking separately in Florence, defended the accuracy of the ads in question, although he maintains he has no control over the negative commercials by outside groups that are flooding South Carolina in the days leading to Saturday's Republican primary.
"I hear that Rick Santorum is very animated that the super PAC ad says that he is very in favor of felons voting," Romney said. "Well, he is! That's his position."
While Santorum complained about the negative commercials during Monday's debate, Romney's three other challengers also tried a host of other attacks in hopes of knocking the former Massachusetts governor off stride.
They kept the spotlight on the multimillionaire's wealth and business dealings by pressing him to release his income tax returns. Romney hesitated but eventually said he might make them public in April. By then, he hopes to have the presidential nomination in the bag.
Speaking to reporters Tuesday, Romney seemed to qualify that even farther, suggesting that he would release just one year of his tax returns - not the six previous years that President Obama released or even the two years that John McCain released in 2008. "People will want to see the most recent year," Romney said.
Romney also came under heavy pressure in the debate on the issue of his job-creation record at his former private equity firm Bain Capital, and his evolving views on abortion. Blamed for the tide of negative commercials, Romney stressed the independence of the super PACs that have been running ads in his behalf against Santorum, former House Speaker Newt Gingrich and other rivals.
On Tuesday, Santorum said that by refusing to condemn the ads, Romney "supports lies, promotes lies and stands behind those lies."
Santorum was upset about an ad that says he "even voted to let convicted felons vote." Santorum complained that the TV spot, while referring to "felons," shows someone in an orange prison jumpsuit, suggesting Santorum would allow felons to vote while still incarcerated. Santorum has supported voting rights only for those who have served their sentences and been released.
But Romney noted that "people who have been released from prison are still called felons if they've committed felonies."
Meanwhile, Gingrich picked up the support of South Carolina Lt. Gov. Ken Ard, who appeared with him in Florence, calling the former U.S. House speaker the smartest and toughest candidate. Romney already has the more coveted endorsement of Gov. Nikki Haley, a tea party favorite, however.
Monday's night's debate was as fiery as any of the more than dozen that preceded it. Romney, the man to beat after back-to-back wins in the Iowa caucuses and the New Hampshire primary, took heat not only from Gingrich and Santorum, but also from Rick Perry and Ron Paul.
The five will meet again in debate in Charleston Thursday night, the last time they will share a stage before the primary two days later.
Monday night, Romney said that while he might be willing to release his tax returns, he wouldn't do so until tax filing time. The multimillionaire former businessman didn't get much gratitude from his rivals, who want him to release the information in time to influence South Carolina voters going to the polls on Saturday.
Gingrich was quick to suggest Romney wouldn't delay for months if he had nothing to hide and that his hesitation wouldn't sit well with voters. "Last night weakened him," Gingrich told CBS' "This Morning" on Tuesday.
Romney seemed hesitant when confronted with the tax issue on stage. He at first sidestepped calls from his rivals to release his returns, then said later that he'd follow the lead of previous presidential candidates.
"I have nothing in them that suggests there's any problem and I'm happy to do so," he said. "I sort of feel like we're showing a lot of exposure at this point," he added.
The first Southern primary could prove decisive in the volatile contest. Gingrich has virtually conceded that a victory for Romney in South Carolina would assure his nomination as Democratic President Barack Obama's Republican rival in the fall, and none of the other remaining contenders has challenged that conclusion.
That only elevated the stakes for Monday night's debate, where the attacks on Romney often were couched in anti-Obama rhetoric.
"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," said Gingrich.
The five men on stage also sought to outdo one another in calling for lower taxes. Texas Rep. Ron Paul won that competition handily, saying he thought the top personal tax rate should be zero.
In South Carolina, a state with a heavy military presence, the debate took on a martial tone at times.
Gingrich drew strong applause when he said: "Andrew Jackson had a pretty clear idea about America's enemies. Kill them."
Perry won favor from the crowd when he said the Obama administration had overreacted in its criticism of the four Marines who were videotaped urinating on corpses in Afghanistan.
Gingrich and Perry led the assault against Romney's record at Bain Capital, a private equity firm that bought companies and sought to remake them into more competitive enterprises, with uneven results.
"There was a pattern in some companies ... of leaving them with enormous debt and then within a year or two or three having them go broke," Gingrich said. "I think that's something he ought to answer."
Perry referred to a steel mill in Georgetown, S.C., where, he said, "Bain swept in, they picked that company over and a lot of people lost jobs there."
Romney said the steel industry was battered by unfair competition from China. As for other firms, he said, "Four of the companies that we invested in ... ended up today having some 120,000 jobs." And he acknowledged, "Some of the businesses we invested in were not successful and lost jobs."
It was Perry who challenged Romney to release his income tax returns. The Texas governor said he has already done so, and Gingrich has said he will do likewise later in the week.
"Mitt, we need for you to release your income tax so the people of this country can see how you made your money. ... We cannot fire our nominee in September. We need to know now," Perry said.
Later, a debate moderator pressed Romney on releasing his tax returns. His response meandered.
"If that's been the tradition I'm not opposed to doing that," Romney said. "Time will tell. But I anticipate that most likely I'm going to get asked to do that in the April time period and I'll keep that open."
Prodded again, he said, "If I become our nominee ... what's happened in history is people have released them in about April of the coming year, and that's probably what I'd do."
April is long after the South Carolina primary and the Republican nomination could easily be all but decided by then, following Super Tuesday contests around the country in March.