(Image Credit: AP Photo/Susan Walsh)

POLAND, Ohio - Casting himself as a strong decisive leader and his opponent as a flip-flopper, President Obama slammed Mitt Romney today for changing his position on what to call the individual mandate.

"When you hear all these folks saying, 'Oh, no, no, this is a tax, this is a burden on middle-class families,' let me tell you. We know because the guy I'm running against tried this in Massachusetts and it's working just fine, even though now he denies it," he told supporters at a campaign event at Dobbins Elementary School.

The criticism comes after Obama accused Romney in a local interview of changing his position for political purposes.

The Supreme Court upheld the president's signature health care law last week, saying its mandate that virtually all Americans buy health insurance was legal under Congress' power to levy taxes.

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While the ruling was a huge political victory for the president, Republicans have accused him of imposing a tax.

"Basically, what we say is, you know what, if you have health insurance, you're all good. If you don't have health insurance, we'll help you get it," the president explained today.

"If you can afford to buy health insurance and you don't get it, so that you force us to pay for your health care when you get sick or you get in an accident, that ain't right. So what we're going to do is, we're going to charge you a penalty to make sure that you're not unloading those costs on everybody else," he said.

Despite the Supreme Court's ruling, the president continues to insist that the individual mandate is a "penalty," not a tax.

"It will affect less than 1 percent of the population, because most Americans are responsible and do the right thing," Obama said. "I make no apologies for it. We're going to keep it moving forward. It was the right thing to do two years ago; it's the right thing to do now."

During his 2008 campaign, Obama repeatedly promised not to raise taxes on middle-class families and he has adamantly denied that the mandate in his signature legislation amounted to a tax.

"For us to say that you've got to take a responsibility to get health insurance is absolutely not a tax increase," the president told ABC News' George Stephanopoulos in 2009. "What it's saying is, is that we're not going to have other people carrying your burdens for you anymore than the fact that right now everybody in America, just about, has to get auto insurance.

"Nobody considers that a tax increase. People say to themselves, that is a fair way to make sure that if you hit my car, that I'm not covering all the costs."