The gloves are coming off in Iowa as Sen. Bernie Sanders, I-Vt., slammed former Vice President Joe Biden's "weak" record, warning Democrats that Biden's candidacy won't excite the base enough to defeat President Trump in a general election.

In an interview with The Washington Post published Thursday, Sanders appealed to primary voters to look past Biden's "perceived electability" and instead focus on voters' "appetite for sweeping change."

“It’s just a lot of baggage that Joe takes into a campaign, which isn’t going to create energy and excitement,” Sanders told The Post. “He brings into this campaign a record which is so weak that it just cannot create the kind of excitement and energy that is going to be needed to defeat Donald Trump.”

Sanders pointed to Biden's past support for the North American Free Trade Agreement (NAFTA) as something Trump would attack him for in a debate setting and slammed Biden's fundraising efforts with the "wealthy."

“It doesn’t take much imagination to understand that Trump will be saying, ‘You see this guy? He voted for NAFTA,’” Sanders said. “People are tired of the traditional types of campaigns in which candidates like Joe are running to wealthy people's homes and raising large sums of money."

YANG SWIPES AT BIDEN: 'MAYBE AMERICANS ALL DON'T WANT TO LEARN TO CODE'

CLICK HERE TO GET THE FOX NEWS APP

A senior campaign staffer also took aim at fellow candidates -- former South Bend Mayor Pete Buttigieg and Sen. Elizabeth Warren, D-Mass. -- for going after "wine cave" voters instead of "working-class" voters.

"When you think about it, Warren and Buttigieg are kind of going after that wine cave, kind of limousine Democrat -- and they’re there, kind of important to the whole party,” Sanders' adviser Pete D’Alessandro told the paper. “We’re going to want them when we win the nomination... But a lot of working-class folks like Joe Biden. Joe Biden and the Bernie Sanders campaign are talking to a lot of the same people."