Presidential candidate Bernie Sanders stumped at Northstar Elementary School in Knoxville on New Year's Eve morning.

The Vermont senator, who is running as a Democrat, says Wall Street's "recklessness" destroyed the economy with the subprime mortgage crisis in 2007. For this reason he says big financial institutions should help pay for free college education in the U.S. through a tax on speculation, or high-risk trading.

"When Wall Street went down they came to the middle class of this country and said, 'Help us. Bail us out.' Now it is Wall Street's turn to help the middle class," says Sanders.

Sanders estimates his plan would cost $70 billion annually.

He also says he wants to help people refinance student debt, cap credit interest rates at 15 percent, "break up" big banks, and make it easier for small and medium-sized businesses get loans.

Sanders, a self proclaimed "democratic socialist," has surprised many by his continued success in polls. Analysts attribute this to the public's disillusionment with U.S. politics.

Sanders also puts the blame on socio-economic inequality.

"Millions of people have been arrested, and have police records for possessing marijuana. But not one CEO of a large Wall Street Bank, whose greed and illegal behavior destroyed the lives of millions of people, not one of those guys has a police record," says Sanders. "It turns out that not only are the large financial institutions too big fail, the bankers are too big to jail. And that is a process, between you and me we are going to change."

This evening Sanders is hosting a New Year’s Eve party in downtown Des Moines.

Over the weekend former Arkansas Governor Mike Huckabee is holding several events in central Iowa. Sanders’s Democratic rival Martin O’Malley returns to Iowa late next week.