Hillary ClintonHillary Diane Rodham ClintonProminent Putin critic: If Trump turns me over, I'm dead Dems unveil slate of measures to ratchet up pressure on Russia Trump tweets old video of Clinton talking up 'a strong Russia' MORE accused Bernie SandersBernard (Bernie) SandersSenate to vote Monday on Trump's VA nominee Senate approves resolution warning Trump not to hand over US officials GOP leader blocks resolution backing intelligence community on Russia MORE of criticizing Presidents Obama and Bill ClintonWilliam (Bill) Jefferson ClintonDem senator ties Kavanaugh confirmation vote to Trump-Putin controversy Don't place all your hopes — or fears — on a new Supreme Court justice Why did it take so long for Trump to drain the swamp of Pruitt? MORE because "he wasn't really a Democrat until he decided to run for president."

Responding to Sanders's criticism of her husband's administration, she defended his economic record while pivoting to a common charge from her campaign about how Sanders has also been critical of Obama.

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"I know that Sen. Sanders has also attacked President Obama. He called him weak, called him disappointing, tried to get someone to run against him [in a primary in 2012]," she said during MSNBC's Democratic presidential forum in Nevada two days before the state's caucus.

"Maybe it’s that Sen. Sanders wasn't really a Democrat until he decided to run for president, so he doesn't really know what the past two Democratic presidents did." Sanders, an Independent senator from Vermont, calls himself a democratic socialist.

The crowd, a mix of Clinton and Sanders supporters as well as undecided voters, responded with a mix of cheers and boos.  

"You know it's true," Clinton told the crowd.  

When MSNBC's moderators noted that both candidates had been jeered at some point over the night, Clinton responded, "The facts are our friends, so let's talk about them."

Sanders is the longest-serving Independent lawmaker in Congress. While he's caucused with the Democrats, he never identified as a member of the party until his presidential bid. 

The Clinton campaign doubled down in a statement from communications director Jennifer Palmieri released just minutes after the forum ended.
 
"If Senator Sanders wants to be the standard bearer of the Democratic Party, he should spend less time attempting to tear down the very real accomplishments of two of the most successful presidencies in modern times," the statement said. 
 
"Their records of accomplishing tangible, life changing results for the American people speak for themselves."