Hillary Clinton specifically pointed to the fact that some who know the Vermont senator best have decided to back her in the Democratic presidential primary.
"They are supporting me because they know me," Clinton said of the members of the Vermont congressional delegation. "They know my opponent, too, that is absolutely true."
She also zeroed in on recent news reports that Sanders has raised money from Wall Street for the Democratic Senatorial Campaign Committee. Clinton has come under scrutiny for Sanders for the same thing.
"I haven't just talked, I haven't just given speeches, I have introduced legislation. I have called them out," Clinton said of Wall Street interests, adding that there's nothing wrong with raising money from banks and others.
"There is nothing wrong with that. It hasn't changed (Sanders') view," she said. "Well, it didn't change my view of my vote either."
On Sunday, Bill Clinton blasted Sanders at an event in Milford for derisively labeling opponents as part of the "establishment" when they disagree.
"The online campaign is, 'anybody who doesn't agree with me is a tool of the establishment,'" he said.
Bill Clinton continued that line on Monday.
"It bothers me to be in an election where debate is impossible because if you disagree you are just part of the establishment," he said.
After the event, Bill Clinton told CNN he stood by his comments, but was surprised by them garnering negative attention because "all I did was take it straight out of press reports."
"We need to not try to let people say everybody who is not for me is in the establishment," Clinton said. "I grew up in a crazy age where we loved to have arguments but they were fact based and we discussed things. That is what democracy is."
Bill Clinton, according to people who have talked to him, has no plans to stop his criticism of Sanders on the campaign trail today or in the coming days. He sees his critiques of Sanders as substantive and fair game.
"Sen. Sanders has changed his posture, questioning Hillary Clinton's integrity, intentions and motives," said a Clinton aide. "He just feels that if that is going to be the case, it is fair for him to be held to that same standard and for him to call it out."
Hillary Clinton is currently running behind Sanders in New Hampshire, a fact most Clinton aides are happy to point out in an effort to lower expectations. But Clinton and her aides are aggressively trying to close the gap in the Granite State, hoping that a slim win for Sanders can be spun as an upset for Clinton.
The former secretary of state said Monday that she understands the anger motivating Sanders' young supporters, but blamed their feelings on President George W. Bush's administration, not Barack Obama's.
"I believe that so much of the anger, the insecurity, the fear and worry that people feel now about the economy, about our prospects, about what is going to happen to young people coming out of college with debt, or unable to find a job that really gives them the best possibly opportunities is related to the choices that were made starting in the Bush administration," Hillary Clinton said.
"When I think about what young people today have gone through, what they have known from our country, starting with a horrible attack on 9/11, going into the great recession, there is no wonder that they along with so many of us are saying, wait a minute, we are better than this, we can do more," she said.