Bernie Sanders (I-VT) needs to lighten up on his Democratic opponents, or he risks damaging the party going into this year's election against President Trump, according to The Hill.

According to those complaining, the 78-year-old Sanders will make it harder for Democrats to unify around a nominee after months of taking flack from their own side of the aisle - despite the fact that a Friday poll has him in the lead, and that his no-holds-barred approach may earn him the nomination.

"He needs to stop," said one Democratic strategist who is unaffiliated with any candidates. "It's not helpful and it actually hurts the party. It’s like he didn't learn his lesson the last time. It’s incredibly short-sighted and terrible."

The strategist highlighted Sanders' recent comments in a LA Times editorial board meeting where he said that President Trump will eat Joe Biden's lunch if he is the nominee.

"Joe Biden is a personal friend of mine, so I’m not here to, you know, to attack him, but my God, if you are, if you’re a Donald Trump and got Biden having voted for the war in Iraq, Biden having voted for these terrible, in my view, trade agreements, Biden having voted for the bankruptcy bill. Trump will eat his lunch ," said Sanders.

Sanders has also unloaded on Democratic rival Sen. Elizabeth Warren (D-MA), after giving campaign volunteers a script to tell potential voters that she was appealing primarily to upper-income Democrats and would not attract new voters to the party.

"I was disappointed to hear that Bernie is sending his volunteers out to trash me," said Warren. "I hope Bernie reconsiders and turns his campaign in a different direction."

Bernie Sander’s volunteers are trashing Elizabeth “Pocahontus” Warren. Everybody knows her campaign is dead and want her potential voters. Mini Mike B is also trying, but getting tiny crowds which are all leaving fast. Elizabeth is very angry at Bernie. Do I see a feud brewing? — Donald J. Trump (@realDonaldTrump) January 13, 2020

According to Clinton campaign veterans, this looks like 2016 all over again.

“In and of itself it shouldn't take on too much meaning,” said Philippe Reines, a longtime communications adviser to Clinton. “But if it's a harbinger of tone to come, that's not great. And I say that as someone who doesn't believe the primaries should be a cotillion or game of paddy cakes.” -The Hill

Reines also blames Sanders for not immediately backing Hillary Clinton when she won the nomination - after cheating against him, saying that Bernie "needs to either accept the plain fact — supported both quantitatively and anecdotally — that his supporters did not go all in for Hillary."

"Giving him the benefit of the doubt about his intentions, he still needs to be mindful that at some point he might need to rally millions of people to support someone else. That’s not easy. You can’t just flip a switch. It’s a process. Your supporters have to believe you’re being genuine in your endorsement, and you have to convince them," Reines added.

Sanders allies, meanwhile, take exception to the critics.

"I don't see it any differently than Vice President Biden going after 'Medicare for All," said longtime Sanders ally Larry Cohen, chairman of Our Revolution - an organization which sprung from the 2016 Sanders campaign. "It should be about the issues and when we have differences and believe if something is better, we should say so."