Clinton repeated her accusation that Sanders and his campaign are engaged in an "artistic smear" by using innuendo against her.
Sanders, for his part, declined to join calls -- including from his own spokeswoman -- for Clinton to release transcripts of her paid speeches to big banks, but he didn't reject those calls either.
CNN's Jake Tapper asked Clinton about the implication from the Sanders campaign that Clinton changed her vote on a bankruptcy bill fifteen years ago as a senator.
Earlier in the week, the Sanders campaign had forwarded to reporters comments and writings by Elizabeth Warren, the consumer advocate who is now a senator from Massachusetts. Warren has said that Clinton had agreed with opposing the bankruptcy provision as first lady, but ultimately voted for it years later as a senator.
The accusations by Warren that she changed her vote are not new. CNN wrote about them in 2014. They also featured in the 2008 presidential campaign
, when Clinton said she regretted the vote.
Clinton told Tapper she voted for the bill she didn't like in 2001 as part of a deal to strike a provision about child support she said would hurt women and children. That's the way Congress works, Clinton said.
"That's the way it happens sometimes," she said. "I didn't like the bill any more than I had liked it before. It still had very bad provisions. But I also pushed hard for a deal to protect women and children. So, okay. I held my nose, I voted for it. It never became law."
Clinton bristled at the implication, however.
"This attack by insinuation, by innuendo, is really getting old," she said, arguing the Sanders campaign is "grasping at straws" to make the case she is beholden to Wall Street.
Clinton said she has a tougher plan to take on Wall Street than he does and she'd rather debate those issues.
Earlier this week, Sanders criticized his opponent over her ties to Wall Street at MSNBC's Democratic debate.
"What being part of the establishment is, is in the last quarter, having a super PAC that raised $15 million from Wall Street, that throughout one's life raised a whole lot of money from the drug companies and other special interests," Sanders said Thursday.
Sanders won't join calls for transcripts
Sanders, meanwhile, declined to to join calls for Clinton to release transcripts from her speeches to Goldman Sachs and other big banks, despite mounting pressure from progressives for the Democratic front-runner to do so.
The Vermont senator also ripped a key Clinton surrogate, predicted a close race in New Hampshire's upcoming primary and even exuded confidence that he will do well in South Carolina.
"Do you think she should (release the transcripts), and what do you think would be revealed in those transcripts?" Tapper asked Sanders.
"No idea," Sanders said. "I have no idea what she said and I think the decision as to whether or not to release it is her decision."
"You don't have a position on it at all?" Tapper asked.
"No," the Vermont senator said.
When asked at the debate whether she would release the transcripts, Clinton simply said she would "look into it."
But progressive activists, as well as some Republicans, have put pressure on Clinton over her paid speeches, with some calling on her to release the transcripts. And Symone Sanders, a spokesman for the Vermont senator's campaign, called for the transcripts to be released before Tuesday's primary.
"I think that is a question that is going to live on further, even after this debate is over, and it's a question that deserves to be answered," she said.
A CNN analysis
found Clinton collected at least $1.8 million for at least eight speeches to big banks, including Goldman Sachs and UBS, from the time after her husband, former President Bill Clinton, left the White House until she announced her presidential campaign last spring.
Sanders rips Clinton surrogate
Sanders, however, did not hold back when Tapper asked him about David Brock, the man who runs the pro-Clinton super PAC Priorities USA.
"I happen to like Hillary Clinton, but I am astounded by some of the people that she has hired, including David Brock," Sanders said, questioning his opponent's judgment.
Brock is a recovering "right-wing attack man" and lead a crusade against the Clintons in the 1990s.
Now, however, he is a major Clinton backer and has regularly targeted Sanders. Among other attacks, Brock recently said that a Sanders TV ad didn't feature enough African-American and Latino faces and claimed "Black lives don't matter much to Bernie Sanders."
"David Brock, people will remember, used to be a real right-wing guy who was attacking people like Anita Hill," Sanders said. "This is an African-American law professor who tried to do the right thing, and he admitted it. He said, 'I lied about her.'"
Sanders added, "I just don't understand where the Clinton people are coming from hiring somebody like that. Every day, you know, they're attacking us in one way or the other."
'Don't jinx me'
Sanders did have a 2-to-1 edge in the latest CNN/WMUR New Hampshire tracking poll
as recently as Saturday, but that margin narrowed slightly
in a poll out Sunday.
The Vermont senator believes Tuesday's primary will be a close one.
"We think it's gonna be a close election, we're working really hard," Sanders told Tapper.
It's a sentiment Sanders has echoed for the past five days in the Granite State.
"Don't make me nervous, and don't jinx me," he added.
Both Democratic campaigns have tried to manage expectations for the primary. Clinton has pushed the narrative that Sanders hails from Vermont and thus has an edge with his New England neighbors. In turn, Sanders reminded voters that Clinton won the state in the 2008 primary when she ran against then-Sen. Barack Obama.
The Sanders campaign has said it's insulting to New Hampshire voters to suggest that they would only support him because he's from the New England area.
"Well, in this sense it is. Look, I mean, obviously, Vermont and New Hampshire are separated by a river, we are close states," he told Tapper. "But you know what? Secretary Clinton won this state in 2008. Her husband ran several campaigns in this state.
When we began this campaign here in New Hampshire, we were 30 points down in the polls and she was much better known in this state than I was."
Earlier in the week, Sanders reiterated the same line, telling reporters on Tuesday that Clinton "has very significant political connections."
"She has the support of virtually the entire political establishment here in New Hampshire," he added.
But although Sanders says he's focused on not letting New Hampshire slip away, he believes his campaign will be viable in South Carolina, a state where Clinton is considered to have a significant advantage.
"I think we are the underdog now," Sanders said. "I think we have seen some real momentum there. I think we got a shot at it."