Hitting on a theme seized by President Obama and Democrats in both chambers, Whitehouse said his “Paying a Fair Share Act” would remedy the inequity in the rate some billionaires who earn most of their salary from capital gains, like Buffett, pay in taxes compared to salaried workers like secretaries or janitors.

"Mr. Buffett is the first to express his dismay," at this inequity, said Whitehouse. "Mr. Buffett has called for a correction of this tax anomaly and I agree with him. We should celebrate the success of those earning millions a year but we really don't… need to subsidize that."

Opponents of raising taxes on capital gains, however, point out that the rates that currently exist are designed to incentivize investments, which benefit the economy as a whole.

Whitehouse, who is up for reelection at the end of the year, introduced the bill on Wednesday, a little more than one week after Obama named the "Buffett Rule" in his State of the Union address as a one of his 2012 priorities.