Reid last week said he had "heard" Romney paid no federal income taxes for a decade. Romney, the presumed GOP presidential nominee, released his 2010 tax returns and promised to release 2011 but has declined going further back.
Speculation has been swirling for weeks about how much he has paid in taxes and Reid said Thursday: "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."
Reid said he got the information from an investor at Bain Capital, the venture capital firm Romney headed, but did not provide any evidence.
Sen. Lindsey Graham, R-S.C., appearing on CNN's "State of the Union," called Reid a liar.
"I've been around this town for a while. I actually like Harry. But what he did on the floor of the Senate is so out of bounds. I think he's lying about his statement of knowing something about Romney. So this is what's wrong with America -- ...
"I think he has created an issue here. I think he's making things up. And at a time when the country is just about to fall apart. ... I just cannot believe that the majority leader of the United States Senate would take the floor twice, make accusations that are absolutely unfounded, in my view, and quite frankly making things up to divert the campaign away from the real issues.
Republican Party Chairman Reince Priebus also called Reid a liar.
"I'm not going to respond to a dirty liar who hasn't filed a single page of tax returns himself," Priebus said on ABC's "This Week." "[He] complains about people with money but lives in the Ritz Carlton here down the street. ... This is just a made-up issue."