This equanimity in the face of an increasingly troublesome campaign by Sanders underscores the delicacy of the current moment: Clinton and her backers don’t want to alienate the nearly 10 million voters who’ve rallied to Sanders. They also can’t afford to let Sanders damage Clinton as she attempts to pivot to a general-election matchup with Trump.

“I know that Bernie’s going to be there, and Bernie has just as strong of feelings that Donald Trump should not be president as I do, as Hillary does, as all of us,” said Senator Sherrod Brown of Ohio, a Clinton supporter considered a potential vice-presidential running mate.

WASHINGTON — Top Hillary Clinton supporters are keeping the kid gloves on — for now — as they deal with a defiant Bernie Sanders, despite rising worries that the Vermont senator’s continued crusade is hurting the party’s chances in November.


New polls out Sunday showing Clinton and Trump in a dead heat nationally only increased Democrats’ anxiety.

The stakes are high for Sanders as well. It is almost impossible for him to win enough delegates to clinch the nomination.

How he navigates the final weeks of the primary campaign will determine if the next chapter of his political life is titled “Progressive Powerbroker” or “Senate Pariah.”

If he meets the party’s calls to marshal his troops to Clinton’s defense in November, he would return to the Senate wielding new influence, thanks to his passionate followers, which he could use to pursue the issues he raised on the campaign trail, observers say. If he plays the part of a spoiler, he could find himself crowned the Ted Cruz of the left — despised by his colleagues, with little ability to get anything accomplished.

Tensions between the Sanders campaign and the Democratic establishment flared last week in the wake of a chaotic state party convention in Nevada. Party leaders called on Sanders to condemn his supporters’ disruptive behavior. Sanders, instead, doubled down on the complaints that his supporters haven’t been treated fairly — though he did include a brief condemnation of “any and all forms of violence.”


Sanders’ handling of the Nevada mess upset many Democrats, but most have kept their emotions in check, offering perhaps a few words of disappointment followed by sunny statements that Sanders will do the right thing sooner or later.

“I’m not blaming Bernie on this one. I think he felt an understandable need to defend his supporters, and I think what happened in Nevada is an aberration,” said Senator Claire McCaskill of Missouri, an early Clinton endorser.

McCaskill even critiqued the Democratic leader who has pummeled Sanders the hardest, Democratic National Committee chairwoman Debbie Wasserman Schultz.

The DNC chief slammed Sanders as failing to more fully condemn his supporters’ violence and intimidation in his post-Nevada statement, “and instead added more fuel to the fire,” as she said on CNN.

“The confrontational aspect of it I didn’t think was particularly helpful,” McCaskill said.

Senator Tim Kaine of Virginia, a Clinton ally also generating VP buzz, said Sanders’ post-Nevada statement “wasn’t his best moment.” The bad behavior “should just be condemned straight out and plain, and the notion that well it’s really the party’s fault — I was disappointed in that,” said Kaine, a former DNC chairman.

“But I don’t have any doubt that, I think, relatively quickly, Bernie is going to get solidly on board,” he added.


But beneath the friendly words, a sharp warning to Sanders from Democrats pokes through: Their patience is waning.

“I believe we should follow the [primary] process to the end,” said Maryland Senator Barbara Mikulski, another Clinton supporter. “Bernie needs to do the math then. He also has to really affirm his own principles, that when he signed up to be a Democrat, finally, a few months ago, he signed up for the rules of the Democratic Party.”

And it is no accident that Clinton chose last week to declare herself the presumptive Democratic nominee.

“I will be the nominee for my party,” Clinton said in a CNN interview Thursday. “There is no way I won’t be.”

“I have 3 million more votes. In the case of Senator Obama and myself [in 2008], it was neck and neck in the popular vote,” Clinton said on NBC’s “Meet the Press” on Sunday. “And I want to spend a lot of my time, as you’ve seen me do, really taking on Trump.”

Sanders isn’t ready to take the hint. After Clinton’s Thursday declaration, his campaign spokesman hit back by saying that “millions of Americans have growing doubts about the Clinton campaign.”

“The objective evidence is our campaign is the strongest candidate, campaign to beat Trump,” Sanders said in an interview Sunday on ABC’s “This Week.”

“I don’t want to see the American people voting for the lesser of two evils,” he continued, saying that is how voters see a Clinton-Trump matchup.


Also on Sunday, Sanders endorsed Wasserman Schultz’s Democratic primary opponent in her South Florida congressional district, Tim Canova, and put a fund-raising appeal for Canova on Sanders’ prodigious donor list. Sanders said that if he is elected president, he would replace Wasserman Schultz as DNC chief.

Sticking to the defiant path is not without major risks for Sanders. Before the campaign, Sanders was something of a gadfly, with a short list of legislative accomplishments. Now he is a progressive rock star.

“You can imagine Bernie coming back with a lot of leverage, much more in the Senate where he’s been a minor figure,” said Norman Ornstein, a scholar with the American Enterprise Institute. “The second option is that he comes back as a pariah.”

Sanders’ defenders say that the onus to unite the party doesn’t rest solely on the Vermont senator and that the Democratic establishment needs to do its own reaching out.

His sympathizers — and some Clinton backers, too — think the DNC should accommodate at least some of Sanders’ demands to have a greater influence at the party’s national convention in July. Sanders has threatened a floor fight if his supporters don’t get more seats on key committees that shape the party’s platform and convention rules.

“We’re going to talk with him when he’s ready to talk, and listen to him. And we will take into account what he is asking for,” Clinton said on “Meet the Press” Sunday.


The DNC needs to “go the extra mile to make sure that they provide a forum for the convention that is a fair and level playing field,” said Senator Jeff Merkley of Oregon, the only sitting senator to endorse Sanders.

If Clinton is the nominee, Merkley said, Sanders is “absolutely dedicated” to doing whatever he can to help defeat Trump.

For the party to unify, “it’s going to take each side reaching out. It always does.”

Victoria McGrane can be reached at victoria.mcgrane@globe.com. Follow her on Twitter @vgmac.