The Democratic Congressional Campaign Committee is launching radio and Web ads blasting 21 House Republicans over their refusal to agree to allow a vote on extending middle-class tax cuts.

With the George W. Bush tax cuts set to expire at the end of the year, Democrats and President Obama want to freeze the current rates for those with income under $250,000 per year but let them expire for those making more. The Senate has approved a bill that would do that, but the measure does not have enough support to get a vote in the Republican-controlled House.