(CBS News) Milford, Ohio -- Vice President Joe Biden, picking up on earlier Democratic attacks, on Sunday mocked Mitt Romney's refusal to identify what tax loopholes he would seek to close in order to finance tax cuts.
Appearing on NBC's "Meet The Press," Romney sidestepped questions from host David Gregory about which deductions or credits he would pursue. The former Massachusetts governor said only that he would eliminate "some of the loopholes and deductions at the high end" in trying to "lower the burden on middle-income people."
Romney "said he is going to pay for all of these tax cuts by closing the loopholes, but when asked by Mr. Gregory what loopholes he'd close, he couldn't name one," Biden said as a crowd of more than 700 people supporters laughed.
The Democratic National Committee earlier sent reporters a series of emails about Romney's reluctance to specific loopholes, with one of them sarcastically headlined, "Specifics? What specifics?"Complete coverage: Campaign 2012
"When you give these kinds of tax breaks out to the very, very wealthy, the money's got to come from somewhere," Biden told the crowd. "And guess who? You!"
Democrats also highlighted the reluctance of Romney's running mate, Paul Ryan, to specify any loopholes during Ryan's appearance on ABC's This Week.
The tax issue was among the criticisms former President Bill Clinton leveled against Romney in his speech at last week's Democratic National Convention, arguing: "If they stay with this $5 trillion tax cut plan, they'll have to eliminate so many deductions, like the ones for home mortgages and charitable giving, that middle-class families will see their tax bills go up. Or, two, they'll have to cut all the programs that help to empower middle-class families and help poor kids."
At the same time, however, Republicans and even some Democrats - such as Clinton's former labor secretary Robert Reich -- have taken Obama to task for not offering for specifics of his own in his convention speech.
The Romney campaign also issued a statement criticizing Biden - who demanded on Saturday that reporters "" for his recent statements on Medicare that fact-checkers have found to be misleading or inaccurate.