(CNN) - In a new television ad released Wednesday, President Barack Obama's re-election campaign continued to fuel its attack against Mitt Romney over the Republican presidential nominee's tax plan.
The spot, "Won't Say," accuses Romney of being cagey on the details of his proposal and cites reports, as the campaign has in the past, that claim the Republican challenger would have to raise taxes on the middle class to pay for his plan
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"(Romney) won't reveal what's in his taxes, and he won't tell you what he'd do to yours," the ad's narrator says.
Team Obama has been hammering the GOP ticket since Sunday, when both Romney and his running mate Paul Ryan appeared on morning news shows and failed to name specific loopholes they would close as proposed in their plan.
"It's not what loopholes are out there, but who gets them," Ryan said on CBS. "And we're saying by not having higher-income earners utilize these tax shelters, we can lower tax rates on everybody, because they pay more of their income to taxation."
Ryan said he and Romney would decide on the loopholes by having "a debate out in front" and "work with Congress, work with the public, to find out what are the priorities."
Romney was also asked to name specific loopholes and deductions in an interview.
"Well, I can tell you that people at the high end, high income taxpayers, are going to have fewer deductions and exemptions. Those– those numbers are going to come down," Romney said on NBC.
While Romney insists he would not give tax breaks to the very wealthy-only pledging not to raise their rates–Obama's campaign repeatedly points to a Tax Policy Center report released in August that determined Romney's plan would provide large tax cuts to the wealthiest Americans while increasing the tax burden on the lower and middle classes.
"You could lose the deduction for your home mortgage, college tuition, health care," the ad says. "How much would you pay? Romney just won't say."
The ad will run in the crucial battleground states of Iowa, Nevada, Virginia and Ohio, according to the campaign.
Along with the spot, the Obama campaign also released a memo saying Romney's budget plan falls $6 trillion short of the $11 trillion needed to balance the budget. The memo, by Obama's campaign policy director James Kvaal, says the $5 trillion in revenue Romney has proposed to raise by closing loopholes would require even more in spending cuts, of which Romney has named "less than $2 trillion."
"Romney's tax and budget plans are a riddle wrapped inside a mystery wrapped inside a total sham," Kvaal wrote in the memo.
Romney's campaign responded to the ad Wednesday, calling the spot "another misleading attack" from Team Obama.
“The only candidate running who wants to raise taxes is President Obama. President Obama’s plan to raise taxes on small businesses and job creators is more proof that he doesn’t have a plan to turn around the economy," said Romney spokeswoman After last week’s devastating jobs report, the last thing we need is more taxes. Mitt Romney has a plan to lower rates across the board, spur investment, and finally get the country back on the right track.”