President Barack Obama Monday introduced his plan to trim the deficit, including a "Buffett rule" -- named after billionaire Warren Buffett -- which would ensure that people making over $1 million a year would pay a tax rate as high as the people that work for them.

"Middle class families shouldn't pay higher taxes than millionaires and billionaires," the president declared. "That's pretty straightforward. It's hard to argue against that. Warren Buffett's secretary shouldn't pay a higher tax rate than Warren Buffett. There's no justification for it."

"Anybody who says we can't change the tax code to correct that, anyone who has signed some pledge to protect every single tax loophole so long as they live, they should be called out. They should have to defend that unfairness," he added. "If their pledge [is] to keep that kind of unfairness in place, they should remember the last time I checked, the only pledge that really matters is the pledge we make to uphold the Constitution."

Obama went on to fire back at Republicans who had called his plan class warfare.

"We're already hearing the usual defenders of these kind of loopholes saying this is just class warfare. I reject the idea that asking a hedge fund manager to pay the same tax rate at a plumber or teacher is class warfare. I think it's just the the right thing to do," he said.

"Both parties agree that we need to reduce the deficit by the same amount, by $4 trillion. So what choices are we going to make to reach that goal? Either we ask the wealthiest Americans to pay their fair share in taxes or we ask seniors to pay more for Medicare. We can't afford to do both. Either we gut education and medical research or we've got to reform the tax code so that most profitable corporations have to give up tax loopholes that other companies don't get. We can't afford to do both. This is not class warfare; it's math."