Supported by President Barack Obama, the Buffett rule would impose a minimum tax on the wealthiest Americans.
"When people who make more than a million dollars pay less than a percentage of their income than hardworking, middle class families, then something is wrong," Tammy Duckworth, Congressional candidate, said.
Three Illinois Democrats -- Duckworth, Bill Foster and Brad Schneider -- say that the Buffet rule is a matter of fundamental fairness. All are trying to unseat incumbent Republicans.
At a Tax Day rally in Daley Plaza, tea party activists said the issue goes much deeper than higher tax rates for the super rich. Most there believe the tax code needs an overhaul, and that the debate over the Buffet rule is more about politics than economic unfairness.
They say taxing a comparatively small number of the most wealthy Americans -- like Warren Buffet-- wouldn't amount to a drop in the bucket of national debt, and it ignores what they say as the true antidote.
"Lower taxes. Lower spending," Bob Redpath said.
It's like a gambler who goes to a casino with borrowed money," Irene Sandler said.
Those themes from two sides of the aisle are colliding Monday in the U.S. Senate and will continue to do so in this election year.
"They have no idea what's going on in the rest of the country. The world according to them is Washington," John Turner said.
Taxes are due Tuesday, April 17, because of Emancipation Day, a holiday celebrated in Washington, D.C.