By John Whitesides
SPARTANBURG, South Carolina (Reuters) - Republican presidential candidate Mitt Romney sought on Wednesday to stay away from the issue of how much he pays in taxes a day after acknowledging that his income tax rate is about 15 percent, but a key ally joined rivals' calls for Romney to release his tax returns.
During a campaign speech in Spartanburg, Romney avoided mentioning the comment he made a day earlier that his income tax rate is "probably closer to 15 percent than anything," making it lower than the rate paid by most wage-earning Americans.
The remark put Romney, one of the wealthiest people to ever run for the White House, at the forefront of a national debate over the fairness of U.S. income tax rates. Romney is the frontrunner for the Republican presidential nomination to face Democratic President Barack Obama on November 6.
Romney's efforts to stay away from the issue took a hit earlier in the day when New Jersey Governor Chris Christie, a key ally of the former Massachusetts governor, urged him to release his income tax forms.
Newt Gingrich and Rick Perry, two of Romney's rivals for the Republican nomination, pressed Romney during a debate Monday night to release his tax returns and have suggested he may be hiding something in not releasing his tax forms.
Christie played down the notion that the forms would reveal much about Romney, a former private equity executive at Bain Capital LLC with an estimated net worth of $270 million.
"Let's get all the facts out there. See what the tax returns say. And I think everybody will know that the story is probably much ado about nothing," Christie told the MSNBC program "Morning Joe."
Christie suggested that the attention being paid to Romney's finances was mostly a political drama aimed at undermining the former Massachusetts governor in advance of Saturday's South Carolina primary, the third contest in the state-by-state battle for the Republican nomination.
Christie, mentioned as a possible vice presidential running mate for Romney, has been actively campaigning for Romney, making appearances in New Hampshire and Iowa, the first two states to hold nominating contests.
On the campaign trail in the conservative state of South Carolina on Wednesday, Republican voters who were questioned about Romney's tax returns downplayed the issue.
"I think it's political dirt," said Don Ethier, 66, an undecided voter in Spartanburg. "They're needing something to discredit him, and they're making something out of nothing."
Although most U.S. politicians running for president release their tax returns, Romney does not need to do so, said Lawrence Easler, 66, of Spartanburg. "He's a real successful guy. He earned everything he's got, legally."
Adam Temple, a Republican consultant in South Carolina unaffiliated with any of the presidential candidates, called the flap over Romney's tax rate and returns "a small issue."
"It's not about jobs or how he's gonna create them and it's not about electability," Temple said. "Those are the things South Carolina voters care about. The guy has money."
But Temple said that if Romney wins the Republican nomination and the right to face Obama, "we'd be naive to think the Obama campaign isn't gonna make that an issue."
Romney, who has been reluctant to release his tax returns, said for the first time on Monday that he would release them -- but not until April.
Christie urged Romney to move up that timetable.
"What I would say to Governor Romney is: If you have tax returns to put out, you should put them out. You should put them out sooner rather than later because it's always better to have full disclosure, especially if you're the frontrunner," Christie said on NBC's program "Today."
The questions about Romney's finances gained steam on Tuesday, when he told reporters that most of his income stems from investments, placing him at the 15 percent tax rate for capital gains.
The top effective tax rate for U.S. salary earners is 35 percent.
The South Carolina primary may offer the last chance for conservatives such as Gingrich, a former House of Representatives speaker, and Rick Santorum, a former U.S. senator from Pennsylvania, to slow Romney's momentum.
Gingrich and Perry, the Texas governor, have been eager to paint Romney as out of touch with ordinary voters amid a slow economic recovery, and have pounced on the tax issue.
Gingrich has said he will release his own tax returns this week. Perry already has done so.
Some tax analysts have said Romney's tax returns could shed light on his work at the helm of Bain Capital that could give political ammunition to rivals.
A Wall Street Journal editorial on Wednesday called on Romney to use his returns as a platform to call for a simplified U.S. tax code.
"Mr. Romney could use the opportunity to make the moral and practical case for lower rates and fewer loopholes," the Journal said.
(Additional reporting by Susan Heavey, Colleen Jenkins and Alistair Bell. Editing by David Lindsey)