Democrats pushed the Senate vote to hike taxes on millionaires on Monday, arguing for President Obama's so-called "Buffett Rule".
"When the richest few are making more than ever before they can afford to shoulder their fair share of the burden to make this country prosper," said Senate Majority Leader Harry Reid.
Republicans charged it's not about fairness, it's about votes in November.
"By wasting so much time on this political gimmick- that even Democrats admit won't solve our larger problems - its shown the president is actually more interested in misleading people than he is in leading," countered Minority Leader Mitch McConnell.
Polls show the plan backed by President Obama and billionaire Warren Buffett is popular with voters.
The Buffett Rule would tax families making a million a year at least 30%.
It would affect 433,000 U.S. households, and would raise just $47 billion over ten years.
It also highlights the fact that Mitt Romney is mega-rich.
He's expecting to pay just 15% in taxes on $21 million in 2011 income.
Last weekend Romney was overheard by reporters revealing he wants to lower tax rates for the rich so small businesses that pay those rates can hire more workers.