Updated at 3:45 p.m. ET
(CBS News) An aide for Senate Majority Leader Harry Reid this week revealed some details about the source who allegedly told Reid that Mitt Romney avoided paying taxes for 10 years, only to quickly retract those details.
In a radio interview Wednesday, Reid aide Jose Parra said that Reid's source in Bain Capital, the private equity firm that Romney founded, was a Republican with "direct knowledge" on the subject.
"This person is an investor in Bain Capital, a Republican also, and somebody who has been dealing with Romney's company for a long, long time and he has direct knowledge of this," he said, the Huffington Post reported.
However, Parra later told the Huffington Post that he was retracting his remarks: "I do not know the party affiliation of the source, how long he invested with Bain, or his relationship to Romney beyond the fact that he was an investor with Bain Capital, as Senator Reid has previously stated," he said.
Though some have criticized Reid for passing on hearsay about Romney's taxes,, calling his source at Bain "extremely credible."
There's been some speculation that Reid's source has been Jon Huntsman Sr., the founder of Huntsman Corporation and the father of former presidential candidate Jon Huntsman, Jr. Huntsman's business partner is a managing director at Bain, but Huntsman told the Washington Post that he is not Reid's source.
"That's absolutely false," he said of the speculation. "I have absolutely no knowledge of Bain or Mitt Romney's tax returns."
However, Huntsman -- one of Romney's longtime supporters -- also told the Post that Romney should release his tax returns. Romney released his 2010 tax returns and an estimate for his 2011 taxes but has come under fire for not disclosing more, especially in the context of the debate over tax reform.
"Mr. Romney ought to square with the American people and release his taxes like any other candidate," Huntsman said. "I've supported Mitt all along. I wish him well. But I do think he should release his income taxes."
The Obama campaign, meanwhile, continues toover whether Mitt Romney avoided paying any taxes in years past with a new ad that asks, "Isn't it time for Romney to come clean?"