March 7, 2012 at 1:57 PM ET
Fresh off his victory in six of 10 Super Tuesday states, Republican front-runner Mitt Romney appeared on CNBC and acknowledged that it was impossible to measure the impact of his tax plan.
"It can't be scored because those details are going to have to be worked out with Congress and we have a wide array of options," he said in response to a question by CNBC anchor Becky Quick.
Romney previously has insisted that his plan to cut marginal individual tax rates by 20 percent won't increase the deficit because he would limit deductions and exemptions for the wealthy.
Romney insisted in the interview that he's "getting the kind of support across the party that I need to become the nominee."
He hasn't outlined what those changes would be, and says he'll work with Congress.
Romney also said he would consider changing a provision of the tax code that has benefited high-earning investment fund managers, including himself.
"That's probably something we should take a close look at," he said when asked about the controversial tax treatment of "carried interest."
President Barack Obama, in his 2013 budget plan, called for ending the tax break. He has the support of some Democrats in Congress, where legislation to carry out his proposal has been filed.
"If it's ordinary income, you should treat it as ordinary income," Romney said. "If it's capital gain, you should treat it as capital gain."
He said that a true capital gain involves investment risk, whereas ordinary income does not.
Romney paid an effective tax rate of abut 14 percent for 2010 and expected to pay about 15 percent for 2011, according to tax returns and estimates he released in January.
Unlike most Americans, he gets the bulk of his income from investment profits, dividends and interest. He got about $13 million in 'carried interest' income over the past two years.
One of the wealthiest Americans ever to seek the presidency, Romney's fortune has been estimated at $250 million, much of it made during the years when he bought and sold companies for a profit as an executive at the Bain Capital private equity firm.
Watch the full interview:
Reuters and The Associated Press contributed to this story.