Fresh off polls that show Bernie Sanders increasing his lead over Hillary Clinton in New Hampshire, the Vermont senator went on the attack during the Democratic debate on Thursday night, aiming for what he clearly perceives to be Clinton’s Achilles’ heel: her ties to Wall Street.

In one of the debate’s most impassioned moments, Sanders sought to distinguish himself from Clinton by pointing out that she gets campaign contributions from banks and has taken speaking fees from Goldman Sachs. Asked about how his plan for regulating Wall Street differs from Clinton’s, Sanders argued that it’s hard to crack down on an industry that’s also giving you lots of money.

“Well, the first difference is I don’t take money from big banks,” thundered Sanders. “I don’t get personal speaking fees from Goldman Sachs.” He asked, “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? So it’s easy to say, well, I’m going to do this and do that, but I have doubts when people receive huge amounts of money from Wall Street.”

I don’t get personal speaking fees from Goldman Sachs.

And there certainly is a vast difference between their campaign donors. The securities and investment industry has donated almost $6 million to Clinton’s campaign and to outside groups supporting her–the 4th largest source of her donations, according to the Center for Responsive Politics. In contrast, Sanders has only received $47,000 from securities and investment professionals, the 18th-largest source of donations to his campaign.

Clinton has also given at least two paid speeches to Goldman Sachs (though her fee for those talks is not disclosed, she generally receives about $200,000 per speech). In 2013 alone, she earned $3.15 million from speaking to banks like Morgan Stanley, Deutsche Bank, UBS, Goldman Sachs and other firms.

Riding a populist wave that is also energizing Donald Trump’s campaign, Sanders is homing in on the Wall Street elements of Clinton’s support. After months of saying he wouldn’t make an attack ad, Sanders released a new TV ad, “Two Visions,” last week that clearly takes aim at Clinton. Looking straight at the camera, he blares, “There are two Democratic visions for regulating Wall Street. One says it’s okay to take millions from big banks and then tell them what to do. My plan: Break up the big banks, close the tax loopholes, and make them pay their fair share…Will they like me? No. Will they begin to play by the rules when I’m president? You better believe it.”

Though both candidates talk about strengthening the Dodd-Frank rules that were passed to limit risk-taking on Wall Street in the wake of the financial crisis, Clinton’s proposals don’t go as far as those of Sanders–she has suggested taxing short-term trading and imposing a “risk fee” on big banks with assets over $50 billion. She didn’t directly address Sanders’s accusation except to emphasize that she is committed to adding to the Obama administration’s financial reforms. Clinton did push back by noting that Sanders voted in 2000 to deregulate the financial market in 2000, taking away the ability of the SEC and the Commodities Futures Trading Commission to regulate swaps and derivatives, financial instruments which helped cause the financial crisis.