Tonight's debate is sure to feature language about the One Percent and inequality. Obama will argue that the wealthy – like Romney – need to pay more. Romney will argue that he has no plans to lower taxes for the wealthy, and that taxing the rich won't generate growth.
And Americans will be led to believe that the choice for the White House will have profound impacts on the fates of the One Percent and 99 percent.
A new study, however, shows that the president doesn't really matter when it comes to inequality in America.
The study, called "The Rise of the Super-Rich: Power Resources, Taxes, Financial Markets and the Dynamics of the 1 Percent, 1949-2008, " finds that the president's party affiliation "has no effect" on the share of income held by America's top one percent of earners. (Read more: Millionaires in U.S. On the Rise )
What matters politically, they say, is Congress.
"The president has limited ability to make the sort of legislative changes necessary to affect the top 1 percent without the support of Congress, making Congress the central actor here, " said Thomas W. Volscho, an assistant professor of sociology at CUNY-College of Staten Island, who authored the study along with Nathan J. Kelly, an associate professor of political science at the University of Tennessee.
The study said that there have been many drivers for the rise in inequality in recent decades. The income share of the top one percent grew from 10 percent in 1981 to 23.5 percent in 2007. The authors say that Congress's shift to Republican majorities, diminishing union membership, lower top tax rates, and financial asset bubbles in stock and real-estate markets all "played a strong role in the rise of the 1 percent."
They said that Congress can affect inequality two ways: through taxes and through economic policy. It said Democrats generally favor taxes that redistribute income and policies that produce more "egalitarian" outcomes in the economy.
The authors calculated that every five additional seats held by Republicans in Congress translated into $6.6 billion in additional income (or .08 percent of total income) going to the top one percent of earners.
The study noted that stock markets have an even bigger effect on inequality. A 100 point increase in the S&P 500 adds $39.6 billion to the One Percent's totals.
Of course, there are those who say inequality itself doesn't really matter and is a necessary byproduct of economic growth in today's global, skills-based economy. As for the president's impact, Obama has shown how the bully pulpit can shape the debate over inequality and taxes — even if his efforts to affect either have so far been blocked by Congress. (Read more: CEO Tell Workers They'll Likely Lose Their Jobs If Obama Wins )
Others also say that asset prices and stock markets have a much bigger impact on inequality — since it's largely driven by stock-based pay at the top — than Congress, tax policy or unions do.
But the study suggests that when Romney and Obama start talking tonight about how they will re-shape American wealth over the next four years, their words may be largely symbolic.
-By CNBC's Robert Frank
Follow Robert Frank on Twitter: @robtfrank