(CNN) - Mitt Romney's opposition to Buffett Rule may be "because he's exploiting all of these loopholes" in the tax code, Rep. Henry Waxman charged in a Democratic National Committee conference call on Thursday afternoon.
Waxman launched into Romney for a lack of transparency as Democrats have put the Republican presidential nominee under another wave of pressure to release tax and financial documents.
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"If he's not paying his fair share and he doesn't want other gazillionaires - many of whom are going to be together with him and Vice President Cheney in Wyoming - [they] will continue to avoid their fair share," Waxman said.
Waxman sought to tie what Democrats saw as secrecy employed by former Vice President Dick Cheney to Romney. Cheney hosts a high-dollar fundraiser for Romney on Thursday at his Jackson, Wyoming home.
"Let's not go back to a time - to the years when people acted like they're entitled to keep everything secret, that they're entitled to run the government and the American people are not to be permitted to know what's going on because they know better than the rest of us," Waxman fired.
"This is an elitism. It's a sense that they're better than anybody else - they're entitled to all of the money they have and the rest of us should just grin and bear it because they're the ones in charge," he continued.
Former Sen. Jim Talent of Missouri came to Romney's defense on the issue of tax returns earlier on Thursday in a conference call for reporters organized by the Romney campaign.
"This attempt in the White House to shift away from the real issues in the campaigning is getting to the point of being desperate," Talent said. "Going around these 'release his 2010 tax returns, his estimate for 2011,' he will release the rest of it when it's available and he's going to continue talking about the issues that matter to the American people."
Waxman's comments came as Senate Democratic leader Harry Reid said Romney's limited release of tax and financial documents would be a problem should he arise as a nominee for Senate confirmation.
"He not only couldn't be confirmed as a cabinet secretary, he couldn't be confirmed as dog catcher," Reid charged on Thursday. "As a dog catcher, you'd at least want to get a look at his tax returns."
Waxman echoed Reid's comments, adding on the call that "it's clear that Mitt Romney couldn't even get conformed by the United States Senate if he were being proposed for some cabinet job."
Romney released his 2010 tax returns and an estimate of his 2011 tax year liabilities in January, as well as filed an annual financial disclosure required of presidential candidates.
But Democrats charge that is not enough.
After releasing tax documents, Romney said at a GOP debate in January that "I pay all the taxes that are legally required and not a dollar more."
Prompted by a reporter's question, Waxman said that President Barack Obama's decision to exert executive privilege over documents relating to the "Fast and Furious" gun-running sting is an very different scenario from that in which Romney finds himself.
"A candidate for president does not have the ability to exert executive privilege," he said. "Governor Romney does not have executive privilege to keep his tax information from the ability of the American people to learn how he's made so much money over the years."
– CNN's Dana Bash and Dana Davidsen contributed to this report