Sen. Bernie Sanders slammed Hillary Clinton for her close ties to Wall Street, both through her campaign and through her personal finances.

"I don't take money from big banks," Sanders said Sunday evening during the Democratic debate in Charleston, S.C., when asked about the difference between his policy and that of his chief rival. "I don't get personal speaking fees from Goldman Sachs."

Clinton and her husband have both accepted generous speaking fees from Goldman Sachs, as well as a number of other major banks. Wall Street executives are among the top donors to her presidential campaign.

Clinton has attempted in past debates to dismiss criticism of her connections to big banks, this time accusing the Vermont senator of launching similar attacks against President Obama's campaign donors.

"President Obama has led our country out of the great recession," Clinton said. "Sen. Sanders called him weak, disappointing. He even, in 2011, publicly sought someone to run in a primary against President Obama."

Sanders described that criticism as nothing more than a "difference of opinion" with Obama and doubled down on his attack on Clinton's financial backers.

"Can you really reform Wall Street when they are spending millions and millions of dollars on campaign contributions and when they are providing speaker fees to individuals?" he said. "It's easy to say, 'Well, I'm going to do this or do that,' but I have doubts when people receive huge amounts of money from Wall Street."