President Obama tonight joined an aggressive effort by his re-election campaign to discredit Republican rival Mitt Romney, suggesting the former corporate buyout specialist has been dishonest about his departure from Bain Capital.

His comments, in an interview with ABC affiliate WJLA-TV, come amid swirling questions pushed by Democrats about when Romney formally relinquished responsibility for the firm's activities, which have included ties to bankruptcies and outsourcing jobs overseas.

Romney says his charge ended in February 1999; the Obama campaign contends legal documents show he retained a top role through 2002.

"As president of the United States, it's pretty clear to me that I'm responsible for folks who are working in the federal government and you know, Harry Truman said the buck stops with you," Obama told WJLA-TV's Scott Thuman.

"My understanding is the Mr. Romney attested to the SEC, multiple times, that he was the chairman, CEO and president of Bain Capital and I think most Americans figure if you are the chairman, CEO and president of a company that you are responsible for what that company does," he said.

"Ultimately Mr. Romney, I think, is going to have to answer those questions, because if he aspires to being president one of the things you learn is, you are ultimately responsible for the conduct of your operations, but again that's probably a question that he's going to have to answer and I think that's a legitimate part of the campaign."

Romney - who insists he relinquished an active role in managing Bain in 1999 and says there is no concrete evidence that shows otherwise - called the questions by the president's campaign "ridiculous and disturbing" and "beneath the dignity of the president."

"It's Chicago style politics at its worse and the President promised something better than this last time and he ought to stop it and disavow it and rein in these people who are running out of control."