Over the past few months, President Obama has championed what he calls the “Buffett Rule,” following the disclosure that billionaire Warren Buffett pays a lower federal tax rate than his secretary.

“The Buffett Rule is a principle of basic fairness — it’s the principle that millionaires shouldn’t be paying a smaller share of their income in taxes than people below them on the income scale,” says Seth Hanlon of the Center for American Progress.

This month, Sen. Sheldon Whitehouse (D-R.I.) introduced the Paying a Fair Share Act of 2012, which would turn the idea behind the Buffett Rule into part of the U.S. tax code, requiring all households with incomes above $1 million to pay a minimum 30 percent tax rate.

Hanlon argues that implementing the Buffett Rule would help address the long-term budget challenges the United States faces — by asking the wealthy to contribute rather than by simply relying on budget cuts — and he points out that millionaires can afford it. Doing so, he argues, would go a long way to restoring the faith of American people that the tax system is more fair than not.

(See the seven reasons Hanlon cites for implementing the Buffett Rule.)