Republicans in the Senate on Monday blocked legislation that would require those making more than $1 million per year to pay at least 30 percent in federal income taxes.

Democrats fell nine votes short of the 60 votes needed to advance the Paying a Fair Share Act of 2012, which would have enacted the so-called "Buffett Rule" into law.

Senate Minority Leader Mitch McConnell (R-KY) described the legislation, which had been touted by President Obama for the past several months, as nothing more than a "political gimmick."

“The problem is, we’ve got a President who seems more interested in pitting people against each other than he is in actually doing what it takes to face these challenges head on and to solve them in a bipartisan manner," McConnell said on the Senate floor. "And if anybody had any doubt about that, the President’s relentless focus on this so-called Buffett tax over the past few weeks should have dispelled it."

Although the wealthy are taxed at a higher rate than most Americans, some can drastically reduce their effective tax rate through tax loopholes, particularly when their primary source of income is from long-term capital gains. Approximately 94,500 millionaires pay a lower effective tax rate than millions of families earning less than $100,000, according to the Congressional Research Service (PDF).

If enacted, the Paying a Fair Share Act would generate $47 billion in revenue over the next ten years, according to the Joint Committee on Taxation.

But Republicans had decried the proposed minimum tax on millionaires as "class warfare." Nearly every Republican in Congress has pledged to vote against any tax increase under any circumstance.

According to a CNN poll released on Monday, 72 percent of Americans supported the legislation. About 90 percent of Democrats and 70 percent on independents supported the legislation, while only 53 percent of Republicans supported it.