WASHINGTON -- Multi-trillion dollar financial institutions continue to get richer, exerting more and more control over both America's economy and its political system. The top 20 largest banks' assets are nearly equal to the nation's gross domestic product.

Now, Sen. Sherrod Brown (D-Ohio), along with unlikely ally Sen. David Vitter (R-La.), is launching an effort to break up the taxpayer-funded party on Wall Street.

"The best example is that 18 years ago, the largest six banks' combined assets were 16 percent of GDP. Today they're 64-65 percent of GDP," Brown said. "So the large banks are getting bigger and bigger, partly because of the financial crisis, partly because of the advantages they have."

The progressive Ohio senator sat down with The Huffington Post in advance of his Thursday speech on the Senate floor to discuss the need to address the "too big to fail" problem and the bipartisan support his work is attracting.

"The system is such that the big banks have far too many advantages, bestowed in part by the marketplace, because investors understand and the market understands that government might in fact bail them out, so there is lower risk for investors, and that means that they can borrow money at a lower cost than anybody else can," Brown said, explaining why small- and mid-sized banks are at a disadvantage.

Brown and Vitter announced on Thursday that they were working together on bipartisan legislation to address this problem.