DES MOINES, Iowa >> Hillary Rodham Clinton’s campaign on Sunday defended her donations from Wall Streetby saying she worked to help the financial sector rebuild after the Sept. 11, 2001, attacks and sought to address the abuses that led to an economic crisis.

During the second Democratic debate on Saturday, Vermont Sen. Bernie Sanders put Clinton on the defensive when he said Wall Street had been the major contributor to her campaigns. “Now maybe they’re dumb and they don’t know what they’re going to get, but I don’t think so,” he said.

Clinton accused Sanders of trying to “impugn my integrity” and said that as a New York senator, she helped New York City’s financial hub rebuild. “That was good for New York and it was good for the economy and it was a way to rebuke the terrorists who had attacked our country,” she said, her voice rising.

On Sunday, Clinton campaign spokesman Brian Fallon elaborated, saying in a statement that her work to help the financial industry rebuild after 9/11 “did not mean she ever hesitated to call out and seek to reform the abuses and excesses that led to the economic crisis. She did so early and often.”

Her debate response drew an incredulous reaction on social media sites like Twitter, and the debate’s moderators asked Clinton to respond to one Twitter user, who took issue with her mention of 9/11 to justify the contributions.

“Well, I’m sorry that whoever tweeted that had that impression because I worked closely with New Yorkers after 9/11 for my entire first term to rebuild,” Clinton said. “I had a lot of folks give me donations from all kinds of backgrounds say, ‘I don’t agree with you on everything. But I like what you do. I like how you stand up. I’m going to support you.’ And I think that is absolutely appropriate.”

The exchange highlighted one of Sanders’ main critiques of Clinton: That she has maintained close ties toWall Street executives during her political career and would be less forceful in policing the risky behavior of financial firms that Sanders says led to the economic downturn in 2008 and 2009.

Both Sanders and ex-Maryland Gov. Martin O’Malley support reinstating the Glass-Steagall law which once separated commercial and investment banking but was repealed in 1999 under her husband, President Bill Clinton. The former secretary of state says repealing Glass-Steagall wouldn’t go far enough to curb risks pushed by a shadow banking system.

When Clinton raised Wall Street donations along with 9/11, her Democratic rivals quickly pounced. In the post-debate “spin room,” former Maryland Gov. Martin O’Malley told reporters, “I’ll let her answer that gaffe. I think it was one of the biggest ones of the night.”

Mark Longabaugh, a top Sanders’ adviser, said, “Do I think it’s a legitimate defense? No. I don’t see how you can make those two pieces go together.” He called the exchanges over Wall Street the “pivotal moments of the debate.”

Republicans said Clinton had hidden shamefully behind the 9/11 attacks to deflect attention from her ties to her wealthiest donors. And they signaled that the response would likely find its way into advertising if Clinton becomes the Democratic nominee.

“It’s an intersection between stupid and offensive, and I think that’s going to be a big problem as the campaign heads into the general election,” said Sean Spicer, the Republican National Committee’s chief strategist.

Clinton campaign chairman John Podesta told reporters that Clinton’s “integrity was impugned and what she was saying was that she was proud to represent the state of New York, to help rebuild lower Manhattan.”

“When people attack her and call her quote-unquote the ‘senator from Wall Street,’ they ought to remember that she was instrumental in trying to rebuild an important part of the New York economy,” he said.