07/12/2012 12:30 pm ET Updated Jul 12, 2012

Harry Reid Mocks Mitt Romney's Low Tax Bill, Offshore Accounts (UPDATE)

WASHINGTON -- Citing a new report finding America's tax rates at the lowest level since 1979, Senate Majority Leader Harry Reid mocked wealthy GOP presidential contender Mitt Romney on Thursday for paying even less, implying Romney's lower tax bill was thanks to his offshore accounts.

"The nonpartisan Congressional Budget Office reported this week that in 2009 rates fell to their lowest level in more than 30 years," said Reid (D-Nev.) in a Senate floor speech. "Much of that decline is thanks to President Obama, who has consistently fought to lower taxes for middle-class families over the last three and a half years," he said.

The CBO concluded the low taxes likely extended into 2010 and 2011, although full data were unavailable.

"The average tax rate in this country fell to the lowest rate since 1979 –- 17.4 percent," said Reid, adding, "Of course, that’s still a higher rate than Mitt Romney pays."

Romney paid an overall tax rate of just 13.9 percent in 2010 and estimated he would pay 15.4 percent in 2011.

When the presumptive GOP nominee released those figures, it was assumed that his rate was so low because nearly all of his income came from capital gains, which are taxed at just 15 percent. But recently a furor has erupted over Romney's offshore accounts, which also could be shielding him from taxes.

"Most Americans don’t have the benefit of Swiss bank accounts or tax shelters in the Cayman Islands and Bermuda," Reid said, alluding to Romney's financial situation.

Romney has argued that he does not manage those accounts, that he doesn't know where they are and that his trustees pay all the required taxes.

UPDATE: 4:09 p.m. -- Harry Reid stepped up his criticisms later on Thursday, pointing to a report that Mitt Romney kept working for Bain three years after he said he had left and also mocking Romney's refusal to release more of his tax returns.

"He not only couldn’t be confirmed as a Cabinet secretary; he couldn’t be confirmed as a dog catcher because a dog catcher -- you’re at least going to want to look at his income tax returns," Reid told reporters, before pivoting to the Boston Globe story on Bain. "His SEC filings indicated that he was chief executive officer, sole stockholder, and ran the corporation for at least three more years. And that’s why people who say -- there’s been advertisements where businesses were closed, people laid off, and he says, 'Oh, I wasn’t there. I left in 1999.' As his own operative said, it doesn’t make sense. And it doesn’t.”

Romney's campaign insists, despite the documents, that he had no role in Bain's investments after 1999.