Democrats on Thursday accused Republican presidential contender Mitt Romney of lying about his tenure at Bain Capital, misleading federal securities regulators and being overly secretive about his personal finances.

The Romney campaign hit back hard, charging that President Obama "doesn't tell the truth" and tolerates a staff whose wild claims demean the presidency itself.

The Democratic attacks on Romney were their most aggressive to date and included accusations that Romney is a liar who may have committed a felony by misrepresenting his role at Bain, a venture capital firm, to the Securities and Exchange Commission, or SEC. Romney's refusal to make public several years' worth of tax returns demonstrates a lack of accountability that would disqualify him for a Cabinet post, let alone the presidency, they said.

"He couldn't be confirmed as a dog catcher," said Senate Majority Leader Harry Reid, D-Nev., whose leadership post hinges on the ability of Obama and Democrats to hold their Senate majority.

The concerted attacks on Romney started with a story Thursday in the Boston Globe, claiming Romney had remained CEO of Bain Capital, a company he founded, three years longer than he previously claimed.

Romney said he left the company in 1999 to run the 2002 Winter Olympics in Utah. But the Globe cited government filings from Bain that listed Romney as CEO until 2002.

Obama's deputy campaign manager, Stephanie Cutter, told reporters in a conference call that Romney may have committed a felony by lying to the SEC about his role at the company.

"If he was lying to the American people, then that's a real character and trust issue," Cutter said.

Romney's team hit back, but not until much later Thursday, when campaign manager Matt Rhoades called on Obama to apologize for what he called "the out-of-control behavior of his staff, which demeans the office he holds."

But Democrats were already on a roll trying to tear down Romney, who is running neck and neck with Obama as the president struggles with approval ratings below 50 percent.

Democrats organized a second conference call for reporters with Rep. Henry Waxman, D-Calif., who once chaired a House committee that conducted several investigations into President George W. Bush's administration.

Romney, Waxman said, appeared to be hiding something by disclosing only one year of tax returns and putting some of his money in foreign banks.

"He may be holding back his tax returns because they raise serious questions about what appears to be mysterious finances and possible tax avoidance," Waxman said.

Romney said he has been "scrupulous" in observing the tax code and pledged on the Fox Business Network to release his 2011 tax returns when they are ready.

Romney's campaign responded to the attacks with a new ad that cites analysis from fact-checking news sites that debunk Obama campaign accusations against Romney. "When a president doesn't tell the truth," the ad said, "how can we trust him to lead?"

Bain officials told The Examiner that Romney indeed left in 1999, but that it took time to work out a retirement plan for him.

"He was in Utah, running the Olympics 24/7," a Bain official said.