Getty Images President Obama has cited the argument that Debbie Bosanek, Warren Buffett's secretary, pays a higher effective tax rate than her employer does.

A version of President Obama's "Buffett Rule" has been introduced in the U.S. Senate but it faces an enormous obstacle: strong Republican opposition.

Today, Senator Sheldon Whitehouse, a Democrat representing Rhode Island, formally introduced what he's calling the "Paying a Fair Share Act of 2012."

If passed, it would require that anyone earning more than $1 million a year, including capital gains, would pay a minimum 30 percent federal tax rate.

The bill provides for a phase-in period for those making between $1 million and $2 million to "make sure that no taxpayer is ever in a situation where earning an additional dollar of income will increase his or her taxes by more than that dollar," according to Whitehouse.

In a statement, he says, "There are lots of advantages that come with an enormous income, and that's great because America thrives on capitalism and we all love success; but paying a lower tax rate than regular working families should not be one of those advantages."

In his State of the Union address last week, President Obama cited Buffett's long-standing complaint that he pays a lower effective tax rate than his secretary does.   Debbie Bosanek, Buffett's assistant, watched the speech from Michelle Obama's box.

Buffett argues that the 15 percent tax rate on money made from investments means many very wealthy people like him are not contributing their fair share to fund the government. 

Last August, his New York Times op-ed plea to Congress, "Stop Coddling the Super Rich," helped push the issue into the public dialogue and has been heavily criticized by Republicans and other who oppose any increase in taxes because they think it would discourage the creation of jobs and hurt the economy.

A spokesman for House Speaker John Boehner calls the new bill a "desperate" bid by Obama to "distract attention away from his failed economic policies."  House Republicans "are going to focus on tax policy that actually helps create jobs — not soundbites."

Current Berkshire stock prices:

Class B:

BRK.B loading...

Quote  |  Chart  |  News  |  Profile

[BRK.B  Loading...      ()   ]

Class A:

BRK.A loading...

Quote  |  Chart  |  News  |  Profile

[BRK.A  Loading...      ()   ]

Keep up with Warren Buffett on CNBC.com and follow alexcrippen on Twitter.

Email comments to