Democratic presidential candidate Sen. Bernie Sanders speaks during a campaign rally on May 10, 2016, in Stockton, California.
Justin Sullivan/Getty
Democratic presidential candidate Sen. Bernie Sanders speaks during a campaign rally on May 10, 2016, in Stockton, California.
Now playing
02:24
Democratic leaders, Sanders battle boils over
bernie sanders still feels the bern origwx allee_00011828.jpg
bernie sanders still feels the bern origwx allee_00011828.jpg
Now playing
01:56
Bernie Sanders still feels the bern
bernie sanders democrats trump bannon bts_00000924.jpg
bernie sanders democrats trump bannon bts_00000924.jpg
Now playing
01:18
Sanders: Democrats will work with Trump if ...
Republican presidential candidate Donald Trump addresses a rally against the Iran nuclear deal on the West Lawn of the U.S. Capitol September 9, 2015 in Washington, D.C.
Chip Somodevilla/Getty Images North America/Getty Images
Republican presidential candidate Donald Trump addresses a rally against the Iran nuclear deal on the West Lawn of the U.S. Capitol September 9, 2015 in Washington, D.C.
Now playing
02:40
Can Trump be trusted with nuclear weapons?
SANTA MONICA, CA - JUNE 07:  Democratic presidential candidate Senator Bernie Sanders (D-VT) greets supporters at an election-night rally on June 7, 2016 in Santa Monica, ia. Hillary Clinton held an early lead in today's California primary.  (Photo by Scott Olson/Getty Images)
Scott Olson/Getty Images
SANTA MONICA, CA - JUNE 07: Democratic presidential candidate Senator Bernie Sanders (D-VT) greets supporters at an election-night rally on June 7, 2016 in Santa Monica, ia. Hillary Clinton held an early lead in today's California primary. (Photo by Scott Olson/Getty Images)
Now playing
02:20
Five moments from Bernie Sanders' improbable run
security scan
DHS
security scan
Now playing
03:04
Fear, anger over potential 'Muslim registry'
CNN
Now playing
02:05
Bernie Sanders says he will work with Donald Trump
Student slams Clinton
Youtube/David K
Student slams Clinton
Now playing
01:15
Student bashes Clinton ... at Clinton event
dnc convention roll call brother larry sanders sot _00012118.jpg
dnc convention roll call brother larry sanders sot _00012118.jpg
Now playing
01:23
Bernie Sanders gets emotional at DNC roll call
Sen. Bernie Sanders speaks to reporters in Oakland, California. May 30, 2016.
CNN
Sen. Bernie Sanders speaks to reporters in Oakland, California. May 30, 2016.
Now playing
01:36
Secret Service rush stage at Bernie Sanders rally
Bernie Sanders takes the stage at the DNC Convention
CNN
Bernie Sanders takes the stage at the DNC Convention
Now playing
01:00
Bernie Sanders takes the DNC stage, crowd goes crazy
Bernie Sanders speaks to members of the press before being introduced at the Allen Temple Baptist Church in Oakland, California on May 30, 2016.
JOSH EDELSON/AFP/Getty Images
Bernie Sanders speaks to members of the press before being introduced at the Allen Temple Baptist Church in Oakland, California on May 30, 2016.
Now playing
02:56
It's 'Bernie or bust' for some Sanders supporters
U.S. Sen. Bernie Sanders (I-VT) speaks during a campaign rally with democratic presidential nominee former Secretary of State Hillary Clinton at University of New Hampshire on September 28, 2016 in Durham, New Hampshire.
Justin Sullivan/Getty Images
U.S. Sen. Bernie Sanders (I-VT) speaks during a campaign rally with democratic presidential nominee former Secretary of State Hillary Clinton at University of New Hampshire on September 28, 2016 in Durham, New Hampshire.
Now playing
02:51
Sanders walks fine line on Clinton hacked audio tape
Bernie sot 3
CNN
Bernie sot 3
Now playing
02:23
Sanders' new message to his supporters
Getty Images
Now playing
03:20
Who voted for Sanders and can Trump win them over?
FAIRFIELD, CA - JUNE 03: Democratic presidential candidate, U.S. Sen. Bernie Sanders (D-VT) speaks during a campaign rally at Cloverdale Municipal Airport on June 3, 2016 in Cloverdale, California. Five States including California will hold the final Super Tuesday primaries next week. (Photo by Ramin Talaie/Getty Images)
Ramin Talaie/Getty Images
FAIRFIELD, CA - JUNE 03: Democratic presidential candidate, U.S. Sen. Bernie Sanders (D-VT) speaks during a campaign rally at Cloverdale Municipal Airport on June 3, 2016 in Cloverdale, California. Five States including California will hold the final Super Tuesday primaries next week. (Photo by Ramin Talaie/Getty Images)
Now playing
02:07
What the end of the Sanders primary campaign looks like

Story highlights

Bernie Sanders' backers are unhappy with how they were treated at the Nevada state convention this weekend

Some Democrats are now worried about violence at the national convention in Philadelphia

Sanders' campaign accuses DNC chairwoman of "throwing shade"

(CNN) —  

It was really just a matter of time.

With the Democratic presidential primary in its twilight, frustration within the ranks over the party’s handling of the primary process spilled out this week as Bernie Sanders supporters lashed out at party leaders, arguing that their candidate has been treated unfairly.

The public outpouring of anger began last weekend at the Nevada Democratic Party convention, where Sanders supporters who said Hillary Clinton’s backers had subverted party rules shouted down pro-Clinton speakers and sent threatening messages to state party Chairwoman Roberta Lange after posting her phone number and address on social media.

That led Democratic National Committee Chairwoman Debbie Wasserman Schultz, Senate Minority Leader Harry Reid and other top party leaders to demand an apology and publicly ruminate on the possibility of violence at the Democratic National Convention in July as they prepare for a general election battle with Donald Trump.

Obama administration officials on Wednesday played down concerns about escalating tensions, likening the race to the 2008 primary fight between Clinton and then-Sen. Barack Obama.

But Sanders isn’t backing down. A campaign spokesman said Wednesday that the campaign was “looking into” whether to ask for a recount in Kentucky, where Sanders narrowly lost on Tuesday night, and he fired up his crowd in Southern California Tuesday night by calling out the Democratic establishment.

Dems’ new fear: Sanders revolt could upend Democratic convention

The Sanders campaign on Tuesday did condemn unruly behavior from supporters and those who made threats to party leaders, but made clear it is sticking with its stance that the party is subverting the process in a way that benefits Clinton.

“These claims that our campaign is sort of fomenting violence in some way are absolute nonsense,” Sanders campaign manager Jeff Weaver told CNN’s Wolf Blitzer Tuesday night, adding that the campaign “absolutely, categorically” condemns any threatening behavior.

The breakdown in civility comes after what has otherwise been a comparatively polite campaign season for Democrats, but the frustration exposes a rift in the party and undercuts the notion that Clinton will be able to march into the Democratic convention this summer with a party unified behind her.

Throughout the year, Sanders and his supporters have complained about the nomination process and ways they believe it has helped Clinton, including debates held on Saturday nights, closed primaries in major states such as New York, and the use of superdelegates – essentially free-agent party and union stalwarts who are overwhelmingly backing Clinton.

Changing superdelegate rules would still leave Sanders behind

“The problem is that there are long-simmering concerns about unfair treatment out in the Nevada Democratic Party,” Weaver added. “We are not going to allow the millions of people who supported Bernie Sanders to be sort of rolled over in places like Nevada by the way they handled that convention.”

Earlier on Tuesday, Sanders released a statement suggesting that his supporters were justified in feeling like the party has given them a raw deal.

“If the Democratic Party is to be successful in November, it is imperative that all state parties treat our campaign supporters with fairness and the respect that they have earned,” Sanders’ statement read. “Unfortunately, that was not the case at the Nevada convention. At that convention the Democratic leadership used its power to prevent a fair and transparent process from taking place.”

In an interview with CNN, Wasserman Schultz said that statement wasn’t enough.

“I was deeply disturbed,” she said. “The senator’s response was anything but acceptable. It certainly did not condemn his supporters for acting violently or engaging in intimidation tactics and instead added more fuel the fire.”

Sanders campaign: Wasserman Schultz ‘throwing shade’

The DNC chairwoman, however, said she has not spoken directly with Sanders, but that her staff has been in touch with the Vermont senator’s campaign. She also pushed back against Sanders’ accusation that the party had rigged the system against him.

“We’ve had the same rules in place that elected Barack Obama. These rules were adopted for state parties all across the country in 2014,” she said. “They were followed and even if the Sanders supporters were frustrated, there is never, under any circumstances, a place for violence and intimidation to be resorted to in response.”

On CNN’s “New Day” Wednesday morning, Weaver accused the DNC chairwoman of “throwing shade.”

“We can have a long conversation about Debbie Wasserman Schultz and how she’s been throwing shade on the Sanders campaign,” Weaver said.

“I gotta say it’s not the DNC,” he added. “By and large the DNC has been very good to us, but not Debbie Wasserman Schultz.”

Wasserman Schultz brushed off Weaver’s comments later in the day.

“My response to that is hashtag SMH (shake my head),” Wasserman Schultz told Blitzer on “Wolf.” “We need to focus on one thing: get through this primary and work to prepare for the general election and make sure that we can continue to draw the contrasts between either one of our really fine candidates who are focused on helping people reach the middle class and make sure that we get equal pay for equal work and create jobs and not let the Republicans take health care away from 20 million Americans.”

’He should get things under control’

Speaking to reporters in Columbus, Ohio, on Wednesday afternoon, Vice President Joe Biden said if such disruption happens again, “He’s going to have to be more aggressive in speaking out about it.”

“But here we are in May, as was pointed out,” Biden continued. “Hillary was still in this in May, in June. I’m confident that Bernie will be supportive if Hillary wins, which the numbers indicate will happen. So I’m not worried. There’s no fundamental split in the Democratic Party.”

Leading congressional Democrats also pushed Sanders to rein in his supporters. Reid called Sanders’ response “a test of leadership” for Sanders, and a source in his office told CNN that the Nevada senator is waiting to hear from the senator himself on the matter.

“The convention was Saturday. It’s now Wednesday afternoon. And he hasn’t spoken about it,” the source said.

California Democratic Sen. Barbara Boxer, who spoke on behalf of Clinton at the Nevada convention, condemned the behavior.

“He should get things under control,” Boxer said. “We’re in a race that is very critical. We have to be united.”

“This is a character moment for Bernie Sanders. He’s got to figure out how he’s true to his values and his ideals fully,” said CNN political commentator Van Jones.

“I think Hillary and Bernie both misunderstand this movement. I think Hillary just sees it as just a bunch of rowdy kids that at some point will just calm down and fall into line,” he said, later adding, “I think Bernie actually only sees the good in his followers. I think Bernie really misunderstands there is a nasty edge to his following that he’s not taking seriously enough.”

Sen. Tim Kaine criticized Sanders’ responses in the wake of reports that Democrats felt threatened at and following the convention.

“What he did yesterday was sort of say it’s the party’s fault,” Kaine told CNN. “That deflection of responsibility is not leadership.”

Kaine added that the angry protests could be “dirty tricksters in the crowd” and not just Sanders’ supporters.

“I don’t think we should assume that all of the people raising hell are Bernie people,” Kaine said.

Sanders goes after the establishment in fiery speech

Speaking in Southern California Tuesday night, Sanders fired up the crowd by calling out the Democratic leadership.

“The Democratic Party is going to have to make a very, very, profound and important decision. It can do the right thing and open its doors and welcome into the party people who are prepared to fight for real economic and social change. That is the Democratic Party I want to see.” Sanders said.

“I say to the leadership of the Democratic Party: Open the doors, let the people in! Or the other option for the Democratic Party, which I see as a very sad and tragic option is to choose and maintain its status quo structure, remain dependent on big money campaign contributions and be a party with limited participation and limited energy,” he said.

The crowd responded by chanting, “Bernie or Bust!” the equivalent of the Republican #NeverTrump slogan for the Democratic race.

His speech barreled through his list of Clinton contrasts, comparing his stances with her (and criticizing those stances) on minimum wage, fracking, breaking up the big banks, and her use of super PACs.

In response to the chaos in Nevada, Clinton campaign manager Robby Mook simultaneously praised the passion and participation of Sanders’ supporters while adding that Clinton believes that “no one should be intimidated, harassed or threatened in this process.” He called on them to focus that energy on unifying the party, a task that could be difficult given the raw feelings many Sanders supporters have for Clinton after the primary.

“Supporters of both Clinton and Sanders deserve respect for the work they have put into their campaigns,” Mook said. Ultimately, we are confident that the passion and