A top adviser to Hillary ClintonHillary Rodham ClintonTrump scores heavyweight establishment Republicans on fundraising team Romney should endorse Clinton Trump aide: Trump paid 'lowest tax rate possible' MORE is accusing Bernie SandersBernie SandersSanders requests recanvass of Kentucky primary Sanders fundraising for state-level candidates The Hill's 12:30 Report MORE of running the “most negative” Democratic primary campaign in history.
“I think, in fact, he’s probably running the most negative campaign of any Democratic presidential candidate … in a presidential primary season, yes,” said Joel Benenson, Clinton’s senior campaign strategist.
“I think he’s kind of ‘feeling the Bern’ as he’s getting more scrutiny,” Benenson added, mocking a slogan used by supporters of the Vermont senator.
“It seems like once you’re not with him, you become a vocal point of his attacks. I do think it’s been extremely negative and I think it’s unfortunate.”
Benenson, formerly a top pollster to President Obama, said he doesn't recall the 2008 race being as contentious.
“I was on [President] Obama’s side then,” he said. "I don’t think we had the range of negativity on either side.”
Sanders has repeatedly vowed his campaign would reject personal attacks.
He is sharpening his criticism of Clinton, however, as he runs close with the Democratic front-runner in crucial early voting states.
The former first lady has the edge nationwide, however. Clinton has a nearly 15-point lead over Sanders across the country, according to the latest RealClearPolitics average of polls.