DURHAM, NH— It was the sharpest, most caustic debate yet for Democratic presidential candidates Hillary Clinton and Bernie Sanders.

Clinton on Thursday night went after Sanders for his suggestions that she is a captive of Wall Street interests, calling on him to end a “very artful smear that you and your campaign are carrying out.”

Sanders didn’t back down, pointing out the millions that Clinton has collected from financial interests in speaking fees and campaign contributions over the decades.

“I am very proud to be the only candidate up here … who’s not raising huge sums from Wall Street and special interests,” he said.

New Hampshire votes Tuesday in the nation’s first primary to collect delegates for the party’s nominating convention later this year.

The latest debate offered fresh evidence of how the race for the nomination, once considered a sure bet for Clinton, has tightened in recent weeks.

Clinton reported that her campaign had raised $15 million in January — $5 million less than Sanders and the first time she’s been outraised by her opponent. Her finance director called the numbers “a very loud wake-up call.”

The Vermont senator held the former secretary of state to a razor-thin margin of victory in Iowa’s leadoff caucuses on Monday, and polls show he has a big lead in New Hampshire.

Clinton’s prospects are much stronger in the voting after New Hampshire, as the race moves on to states with more diverse electorates.

In their debate, Clinton and Sanders argued over who has the liberal credentials to deliver on an agenda of better access to health care, more affordable college, fighting income inequality and more.

Clinton said Sanders could never achieve his ambitious and costly proposals.

Sanders persisted with his suggestions that Clinton’s loyalties were colored by a reliance on big corporate donors.

“Secretary Clinton does represent the establishment,” he said. “I represent — I hope — ordinary Americans.”

Sanders focused much of his fire on what he says is a political system rigged against ordinary Americans. He spoke of Wall Street executives who destroyed the economy and walked away with no criminal record.

“That is what power is about, that is what corruption is about,” he said.

Clinton insisted that her regulatory policies would be tougher on Wall Street.

Asked if she would release transcripts of her paid speeches to Wall Street interests and others, Clinton was noncommittal — “I’ll look into it.” She had struggled a day earlier to explain why she accepted $675,000 for three speeches from Goldman Sachs.

On foreign policy, Sanders renewed his criticism of Clinton for her vote as a senator to authorize the war in Iraq, a vote she later said was a mistake.

Clinton retorted: “A vote in 2002 is not a plan to defeat ISIS. We have to look at the threats that we face right now.”

___

Benac reported from Washington. Associated Press writer Laurie Kellman in Washington contributed to this report.