Is Mitt Romney 'hiding something' as Reid claims?

Presidential candidate Mitt Romney denied unsubstantiated claims made by Nevada Senator Harry Reid that Romney is 'hiding something' by refusing to release more of his tax returns. Returns that Romney has made public show that he paid a lower tax rate than most Americans in 2010. 

Put up or shut up, says Mitt Romney. Just sayin', retorts Harry Reid. For both men, it's a taxing situation.

Romney demanded Thursday that the Democratic Senate leader back up the story he's been passing around this week that an investor with Romney's old firm, Bain Capital, has told him that Romney didn't pay any taxes for 10 years.

Reid offers no evidence to substantiate the claim — he even says he's not sure it's true — and won't reveal who made it. For the Nevada Democrat, the claim explains why Romney is adamant about not releasing more than a year or two of his tax returns.

Romney went on conservative radio host Sean Hannity's show Thursday morning to brand the claim untrue.

"Well, it's time for Harry to put up or shut up," Romney said. "Harry's going to have to describe who it is he spoke with because of course, that's totally and completely wrong."

Romney added: "It's untrue, dishonest, and inaccurate. It's wrong. So I'm looking forward to have Harry reveal his sources and we'll probably find out it's the White House. Look, the Obama campaign is going to do everything in its power to try and talk about anything besides the president's record."

Reid repeated the claim on the Senate floor. Following Romney's response, he released a statement saying that "it's clear Romney is hiding something."

"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," Reid said. "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."

Romney has released his 2010 federal tax return and a summary of his 2011 return. In 2010, he paid 13.9 percent tax on income of $21.6 million. That's a much lower rate than what most Americans pay on far less income. Most of Romney's income came from investment gains, which are taxed at a lower rate than earned income.

His wealth estimated at $250 million, Romney has said that his critics will distort and use against him any additional tax information he releases.