NEWTON, Iowa— Hillary Clinton's campaign slammed Bernie Sanders for "making a misleading argument" about the former secretary of state's "toughness" on Wall Street.

"While Senator Sanders pushes proposals scrutinized as unachievable and lacking detail beyond a slogan, Clinton has the strongest, most comprehensive plan to tackle risks on Wall Street and in the financial sector," the Clinton campaign said in a statement Thursday.

Wall Street regulation has been one of the hallmarks of Sanders' campaign to fight "the millionaires and billionaires buying our democracy" and has helped him gain prominence in both Iowa and New Hampshire. But with days away from the first caucus, the Sanders camp released an ad emphasizing the importance of regulations.

"Our economy works for Wall Street because it's rigged by Wall Street and that's the problem," the Sanders ad, entitled "The Problem," says.

While the ad does not directly attack Clinton, her the former first lady's campaign directly responded to Sanders at a town hall in Newton, Iowa on Thursday afternoon, telling the crowd that "my friends [in the Democratic primary] don't go far enough. She explained that the investment banks, insurance conglomerates, mortgage companies that contributed to the economy's downfall.

"Here's what I want you to know we already have that in the law thanks to Dodd-Frank," Clinton said "We have that authority, you don't need to elect a president to get that authority, you just need to have a president who understand what it means and how to apply it."

On the campaign trail, Sanders argues that while Dodd-Frank has "made the banking system somewhat safer" it didn't go far enough and the United States should re-implement a Depression-era prohibition on investment banking by commercial banks called Glass-Steagall and impose stricter regulations. In contrast, Clinton is opposed to implementing a new Glass-Steagall.

The two Democrats are running neck and neck in Iowa.