DURHAM, N.H. » It was the sharpest, most caustic debate yet for Hillary Clinton and Bernie Sanders.

A fiery Clinton 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. He kept coming back to 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 does not have a super PAC, who’s not raising huge sums from Wall Street and special interests,” he said.

Five days before New Hampshire votes in the nation’s first primary, Clinton and Sanders head back to the campaign trail today. Thursday night’s intensifying jabs and pokes gave voters something to talk about. And they were fresh evidence of how the race for the nomination, once considered a sure bet for Clinton, has tightened in recent weeks.

Another sign of the new dynamic: 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.”

Sanders held the former secretary of state to a whisper-thin margin of victory in Iowa’s leadoff caucuses, and polls show he has a big lead in New Hampshire. Clinton, who beat Barack Obama in New Hampshire eight years ago, is determined to at least narrow the gap before Tuesday’s vote. Her prospects are much stronger in primaries and caucuses after New Hampshire, as the race moves on to states with more diverse electorates that are to her advantage.

The increasingly contentious Democratic race was the latest twist in an election campaign that, until recently, had been dominated by the crowded and cacophonous field of Republicans, spread all across New Hampshire.

Jeb Bush, his campaign lagging, brought in mom — Barbara Bush — who once suggested the former Florida governor shouldn’t run because the country has “had enough Bushes.” But the former first lady was all praise for her son today morning as she joined him on a round of television interviews.

“He’s honest, dependable, loyal, relatively funny,” she told CBS as the younger Bush beamed. “Good looking, but funny,”

Donald Trump, who finished second among Republicans in Iowa, stepped up the pace of his campaign and acknowledged he should have had a stronger ground operation in Iowa. After calling for a do-over in Iowa, Trump changed his tune late Thursday and said he was more focused on looking ahead to Tuesday’s contest in New Hampshire.

In their debate, Clinton and Sanders argued over ideas, over tactics and 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.

It was Clinton who was the main aggressor, saying Sanders could never achieve his ambitious and costly proposals. Then she took after the Vermont senator for his efforts to cast her as beholden to Wall Street interests, saying: “I really don’t think these kinds of attacks by insinuation are worthy of you. And enough is enough.”

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.”

Where Clinton aimed considerable criticism at Sanders, the Vermont senator 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, unwilling to cede the issue to Sanders, insisted that her regulatory policies would be tougher on Wall Street than his.

“I’ve got their number on all that,” she said of “the Wall Street guys.”

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.

Clinton called Sanders’ sweeping proposals on health care and education “just not achievable,” while Sanders countered that Clinton was willing to settle for less than Americans deserve.

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.”

Sanders allowed that while Clinton had been secretary of state, “experience is not the only point. Judgment is.”

On a nagging issue, Clinton was asked if she was sure nothing problematic would come of the ongoing investigation into her use of a private email account and server to handle official messages when she was secretary of state, some of them later classified as top secret.

“I am 100 percent confident,” she said.

When the fireworks had died out at the end of two hours, the two candidates had some conciliatory words for one another, with Sanders declaring, “On our worst days, I think it is fair to say, we are 100 times better than any Republican candidate.”

Benac reported from Washington. Associated Press writers Laurie Kellman and Josh Lederman in Washington contributed to this report.