At Bernie Sanders' first mention of the "leadership of the Democratic Party," boos cascaded through the arena. He upbraided Democrats for several minutes, each line widening the gap between Sanders, with his loyal followers, and the rest of the party whose presidential nomination he seeks.
The caustic late-season battle between Sanders and Hillary Clinton has broadened into a war between Sanders and the Democratic establishment, one amplified by a collision of circumstances.
Unlike most runners-up, Sanders, a lifelong independent, has little desire to preserve his standing in the Democratic Party for future presidential bids. That reduces the ability of party leaders to pressure him to tone down his antagonism as the Democratic contest closes. It makes him more apt to paint Clinton and the party as his targets.
And as the boos of thousands underscored Tuesday night in Carson, many of his followers are loyal to Sanders alone, not the Democratic Party.
Many of them appear to have bought the notion forwarded by Sanders that only he is working for the sort of economic and social advances that many in the party have long sought. Many seem wedded to the questionable math Sanders pushes to persuade them that theirs is a winning campaign and that any other outcome would prove that the Vermont senator -- and they -- had been robbed by an underhanded system.
All that suggests Democrats may face more difficulty this year than they have in the past in binding the primary's wounds en route to the November election.
Party regulars look to the past for comfort, citing the tense 2008 contest between Clinton and Barack Obama that ended in a unified effort that shepherded Obama into the White House. But Clinton faces a tougher task -- an opponent who appears less willing to cooperate, leading a band of supporters who, in many cases, consider Clinton and the Democratic Party abhorrent.
The clash between the Sanders forces and those he considers his opponents surfaced angrily last weekend at the Nevada state party convention, where the final disposition of delegates took place for a February contest that Clinton won by more than 5 points.
A feud over two delegates, out of three dozen from the state, and 4,765 nationwide, exploded into epithet-flinging rage by some of Sanders' backers.
California Sen. Barbara Boxer, who has spent more than three decades in Washington fighting for the sort of liberal proposals backed by Sanders, was shouted down with vulgarities as she delivered remarks supporting Clinton. The head of the Nevada party received death threats against her and her family via text and voicemail.
Three days went by before Sanders, on Tuesday, issued any comment about the drama, and then he blamed the party for not being "fair" to his campaign. He mentioned his opposition to violence as an aside.
On Tuesday night, at the StubHub Center in Carson, he again blamed Democrats for not fully embracing his supporters and spent more time criticizing party leaders than he did aiming fire at presumptive Republican nominee Donald Trump.
"Let me also say a word to the leadership of the Democratic Party," he said, drawing the first of a series of boos aimed at party officials.
"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," he said.
"Or," he warned, "the other option for the Democratic Party, which I see as a very sad and tragic option, is to choose to retain its status quo structure, remain dependent on big money campaign contributions and be a party with limited participation and limited energy and a party which incredibly is allowing a right-wing extremist Republican Party to capture the votes of a majority of working people in this country."
"Now I come from the working class of this country and I will be damned, I will be damned if we will allow the Republican Party who's chosen to represent the rich and the powerful to win the votes of working-class Americans."
At the first of two events in Northern California on Wednesday, Sanders portrayed the establishment as his enemy in milder terms.
"We have had to take on the political establishment in every state, in every state that we have run in," he said in San Jose. "We have had to take on Democratic governors and senators and members of Congress and mayors, literally almost the entire Democratic establishment, and in state after state the people have stood up and helped defeat the establishment."
The White House on Wednesday made a concerted effort to paper over Democratic difficulties.
"I'm confident that Bernie will be supportive if Hillary wins, which the numbers indicate will happen," Vice President Joe Biden said during an Ohio visit. "So I'm not worried. There's no fundamental split in the Democratic Party."
Sanders and his campaign have long bridled at what they see as favoritism toward Clinton by the Democratic National Committee. He also has done little to mask his view that Clinton, and by extension the Democratic establishment, deserve at least part of the blame for the "rigged" economic system and "corrupt" political environment he castigates in every speech.
But his insinuations that only he and his followers "are prepared to fight" for change make him few friends among Democrats who have fought inside the party for similar goals. And his demands that independent voters be allowed into every party primary and that other long-settled rules be changed to his campaign's benefit also rankle.
There is another more basic reason his criticisms ring hollow to many Democrats: Even as he lectures about the superiority of his campaign, he's losing.
Clinton leads by 279 among pledged delegates. Her lead expands to more than 760 when all delegates are counted. The results Tuesday, in two states, changed almost nothing. Sanders picked up a net of just a handful of additional delegates.
To overcome Clinton's lead in pledged delegates, which he told his Carson crowd was a real possibility, Sanders would have to win about 70% of those remaining, a level of support that would exceed anything seen this year.
At this point, despite Sanders' insistence Tuesday night that only his campaign has "the energy, the enthusiasm and the grass-roots capacity" to defeat Trump, it is Clinton who has drawn millions more voters to the polls.
Sanders' gibes against party leaders on Tuesday night marked a new thrust in his stump speech which, with its insistence that he would take his fight all the way to the July convention, suggested that Democratic hopes for a neat finish to the primary season could be dashed.
After months in which Trump's candidacy divided Republicans in a civil war, it now appears that they are further along in their efforts at unity than the Democrats.
That is, in part, because the Democratic Party is convulsing demographically and ideologically, a development masked during the party's eight years in the White House.
During Obama's tenure, Democrats have grown far more liberal. That has meant that some of its voters have left behind the more conventionally liberal Clinton and the party hierarchy that supports her, in favor of Sanders, a democratic socialist.
Young voters, who are more liberal than older Democrats, have flocked to Sanders. He also has the backing of another key group: independent voters who shrug off party alliances.
California, whose Democratic primary allows nonpartisan voters, illustrates the emerging electorate. A USC Dornsife/Los Angeles Times poll found in March that among those planning to vote in the Democratic primary, Clinton held a 7-point lead. Division lay underneath: Among Democrats, she led by 14 points. Among independents planning to cast Democratic primary ballots, Sanders led by 9 points.
Among voters under 30, the poll found, 41% had registered as nonpartisans, and 37% as Democrats. Among those 50 and over, 44% registered as Democrats and only 15% as nonpartisan.
Not surprisingly, given their affection for Sanders, the supporters who show up at his rallies seem unwilling to question his odds of success as they embrace his predictions of victory.
Thousands gathered for Tuesday night's StubHub Center rally cheered lustily when he said that he'd basically tied Clinton in delegates in Kentucky's primary, even though that result did not advance his cause. They cheered again when he said his campaign had won 45% of the pledged delegates overall this year. If they noticed that the figure he cited meant that someone else had won the majority, they did not show it.
What wasn't lost on the crowd was Sanders' casting of Democrats in general and Clinton in particular as complicit in the problems he rails against. Asked if they would vote for Clinton if she wins the nomination, several voters physically recoiled. If that attitude prevails in November, particularly in states less overwhelmingly Democratic than California, her odds of election would grow dramatically weaker.
The Tapia brothers—Christopher, a 23-year-old student, and Jorge, a 27-year-old pharmacy technician—drove to the Carson rally from their home in faraway Fontana. They are dedicated Sanders supporters who have persuaded their parents and a sibling to vote for him as well.
Both wore T-shirts bearing Sanders' face and the logo: "Not For Sale."
"He's not bought for by billionaires, and he's not a war hawk," said Christopher, encapsulating in one sentence two persistent Sanders criticisms of Clinton.
"His record speaks for itself," said Jorge, pointing to Sanders' decades-old support for civil rights and his antiwar stance.
Neither brother could imagine voting for Clinton unless she capitulated and adopted all of Sanders' proposals. And both were confident that Sanders could win the nomination. They were not so keen, however, on the Democratic Party.
Jorge said he had already switched his registration; once a Democrat, he is now a nonpartisan voter. Christopher said he would follow suit after the June 7 primary "to send a message to the Democratic Party."
"If the Democratic Party doesn't choose Bernie—how are you going to get a sense of what the American people want?" asked Christopher. "That's non-democratic."
3:15 p.m. This story has been updated to add comments from Vice President Joe Biden.
2:15 p.m.: Information from Sanders' Wednesday event in San Jose was added.