Mitt Romney lashed back at Harry Reid on Thursday in an interview with Fox News' Sean Hannity, saying the Senate majority leader needs to "put up or shut up" after airing allegations about Romney's taxes.

Reid, a Nevada Democrat, first raised eyebrows Tuesday by saying in a news interview that someone had told him Romney went 10 years without paying taxes. He would only identify his source as an investor in Romney's former venture capital firm, Bain Capital, and he acknowledged, "I'm not certain" it's true.

That didn't stop Reid from taking to the Senate floor Thursday to accuse the Republican presidential candidate again of paying no taxes, part of a broader Democratic attack on Romney for declining to release more than two years of tax documents.

"The word's out that he hasn't paid any taxes for 10 years," Reid said. "Let him prove that he has paid taxes, because he hasn't."

But Romney forcefully denied Reid's allegations on Hannity's radio show Thursday.

"Harry’s going to have to describe who it is he spoke with, because, of course, that is totally and completely wrong," Romney said. "It’s untrue, dishonest and inaccurate. It’s wrong.

"So, I’m looking forward to have Harry reveal his sources, and we will probably find out it’s the White House."

Romney's campaign earlier rejected the majority leader's statement as "shameful."

Reid also raised eyebrows for invoking Romney's late father, himself a one-time presidential candidate.

"His poor father must be so embarrassed about his son," Reid told the Huffington Post.

George Romney, a Michigan governor, released 12 years of tax returns during his unsuccessful bid for the Republican presidential nomination in 1968. His son has released only his 2010 tax return and an estimate for 2011, years when he was preparing for his own presidential bid or already running.

Reid doubled down on the claim late Thursday, firing back at Romney in a written statement.

"People who make as much money as Mitt Romney have many tricks at their disposal to avoid paying taxes," Reid said in a written statement. “When it comes to answering the legitimate questions the American people have about whether he avoided paying his fair share in taxes or why he opened a Swiss bank account, Romney has shut up. But as a presidential candidate, it’s his obligation to put up, and release several years’ worth of tax returns just like nominees of both parties have done for decades.



“It’s clear Romney is hiding something, and the American people deserve to know what it is."

Reid's comments come in the middle of a scathing critique of the former Massachusetts governor's tax plan. The Tax Policy Center, which Romney has called "an objective third party" in the past, noted that his proposal would give benefits to high-income earners while giving a tax increase to middle-class Americans. Romney's camp has disputed that analysis.