04/11/2012 03:52 pm ET

Obama Campaign Swipes At Mitt Romney With Tax Calculator

As Americans file last-minute tax returns over the next few days, the Obama campaign is giving them an opportunity to compare their tax rates to Mitt Romney's.

In a jab at the likely Republican presidential nominee, who famously pays 15 percent or less on his sizable income, an Obama campaign website on Wednesday unveiled a tax calculator that allows users to enter their own income and filing status, and then compares their likely tax rate with Romney's. Many people, of course, will see that they're paying an overall higher rate than Romney, whose wealth is taxed as capital gains rather than income.

The calculator is just the latest element in President Barack Obama's push to promote the Buffett Rule, which would ensure that millionaires pay at least a 30 percent tax rate and thus contribute more than middle-class Americans to the federal treasury. The president has argued for the rule in recent campaign appearances, and the calculator is hosted on his campaign's Pass the Buffett Rule website.

"Mitt Romney opposes the Buffett Rule because he wants to protect tax loopholes and give millionaires like himself trillions of dollars in tax breaks paid for by either increasing the deficit or by cutting programs critical to the middle class and economic growth," the site charges.

Romney's economic advisers attacked the Buffett Rule in a Wednesday conference call, describing it as “obviously politically motivated" and saying it would have little impact on the economy.