Throughout the past month, California Senator Barbara Boxer has developed into one of the most outspoken surrogates for Hillary Clinton’s presidential campaign. She taunted Sanders supporters at the Nevada State Democratic Party convention, and on a separate occasion, she pathologized millennial supporters, saying they like Sanders because he reminds them of their grandpas. However, this smug attitude, which she has adopted, has become a hallmark of the Clinton campaign.

Boxer was elected to the United States Senate in 1992 along with another woman, Democratic Senator Dianne Feinstein. She is retiring after forty years in politics, and has a book out, called, “The Art of Tough,” which is based on an inexact concept that is as hokey as it sounds.

Appearing on MSNBC’s “Morning Joe” on June 1, Boxer reacted to Sanders’ comments on California Governor Jerry Brown’s endorsement of Clinton.

“For Bernie to say that Jerry Brown is establishment is the joke of the day,” Boxer quipped. “And he called me the establishment. They’ll see I have fought a lot of the establishment my entire life. Just because you’re supporting Hillary doesn’t mean you’re ‘the establishment.'”

“It means you’re progressive and you want to see her—She’s just so qualified for this post. She’s just what we need, and I just—Bernie’s my friend for a long time, but you can’t just diss everybody who supports Hillary Clinton.”

But Sanders did not disrespect Brown or Boxer. He said, “In every state that we have gone into, we have taken on the entire Democratic establishment, whether they’re governors or senators (with one exception in Oregon), mayors, and you know what? We have won 20 states. So it is not surprising to me that, you know, we will have the Democratic establishment supporting Hillary Clinton [in California].”

It is fairly clear-cut. Both Brown and Boxer are longtime Democratic politicians, and as such, they are part of the Democratic establishment, whether they have sometimes taken actions the party leadership opposed.

In twenty states which Sanders has won, Democratic politicians, particularly superdelegates, refuse to stand with primary or caucus voters and back Sanders over Clinton.

Boxer recently appeared on “The Leonard Lopate Show” on WNYC radio. She was asked how long it had been since the California primary was hotly contested. With her answer, she dismissed independents and insinuated it would be better if they could not vote in the Democratic primary. She also fell back on the tribalistic talking point that Sanders is not a “real Democrat.”

BOXER: The reason our primary is a little different is because we Democrats allow independent voters into our primary. So, you know, that’s kind of the interesting part.

LOPATE: Well, it be more like the reflection of the general election because independents make up such a large part of the electorate.

BOXER: Well, it’s not reflective because it’s two Democrats—well, supposedly Bernie’s a Democrat—running against each other…

LOPATE: … Supposedly Bernie’s a Democrat? [laughing]

BOXER: Well, he never ran as a Democrat in his life…

LOPATE: But he voted with the Democratic caucus…

BOXER: I’m saying he’s never been a registered Democrat until now. This is a fact. I’m not saying it as a bad thing. I’m saying it as a fact. But the fact is when you open up the closed primary to the independent voters in a primary it’s going to be different.

There is only one reason someone who is a top surrogate for Clinton says on a talk show that Bernie is “supposedly a Democrat.” It is to make Democratic voters think this is a bad thing or reinforce the idea that he is not one of them and cannot be trusted. It is a subtle form of McCarthyism.

Stunningly, Boxer scoffed at independents, who Clinton will need to pull off a victory over Republican presidential nominee Donald Trump. Boxer acted like Democratic National Committee chairwoman Debbie Wasserman Schultz, who has opposed open primaries because Schultz does not think people who are not affiliated Democrats should be able to pick the party’s nominee.

Democratic establishment politicians like Boxer and Schultz believe a Democratic candidate like Sanders, who has appeal across the political spectrum, should not benefit from such broad support during the primary race. They preach the gospel of party loyalty, even as Clinton reaches out to Republicans who share her views on U.S. foreign policy before clinching the nomination.

Young people have consistently been a source of frustration for Clinton and her surrogates. To deal with the issue of how the vast majority of millennials support Sanders, the campaign has opted to lecture and talk down to this demographic, which includes many first-time voters.

Boxer said on SiriusXM radio, “There was a psychologist I heard who said that the young people look at Bernie as their grandpa. You know, ‘Oh it’s my grandpa and he’s gonna do great things for me.’ And so he connected with a whole group of voters who don’t ordinarily vote.”

This is similar to what Clinton said after the Nevada caucus. “It can’t be just about what we’re going to give to you. It has to be about we’re going to build together,” she told young people, as if the only reason millennials support Sanders is because they want free stuff.

Boxer, and the wider Clinton campaign, would rather not address the corporate politics or the hawkishness of Hillary Clinton. They would rather not look inward and reflect on their role in protecting the one percent from movements born out of righteous anger and despair of the 99 percent. So, as has become a cottage industry in news media, they analyze Sanders supporters as if the problem is their “abnormal” behavior.

Yet, nothing can outdo the performance Boxer put on at the Nevada State Democratic Party Convention. She helped fuel one of the more dishonest attacks on the Sanders campaign during the primary, suggesting she feared for her life and specifically older supporters were violent and dangerous.

Boxer went on stage at the convention while many supporters were still irate at the fact that the leadership of the convention was silencing their attempts to participate in the parliamentary-style process. They were booing and heckling before she hit the stage, and she fanned the flames of rage with her remarks.

“I bring a message from Bernie Sanders, and I bring a message from Hillary Clinton. We need civility in the Democratic Party. Civility, because the whole future of the country is at stake,” Boxer said.

“Now, when you boo me, you’re booing Bernie Sanders. Go ahead. You’re booing Bernie Sanders. Bernie is my friend. You want to boo Bernie, boo me. Go on. You’re booing Bernie. You’re booing Bernie,” Boxer jeered. “Let’s hear it for Hillary Clinton. We have the votes. We have the voice. We have victory. Hooray!”

“I grew up in Brooklyn. I am not afraid of bullies. So keep booing, and boo yourselves out of this election. Go ahead—yeah, yeah.” She was grinning at the angry convention crowd.

There is nothing civil about taunting Sanders supporters and rubbing their faces in the fact that Clinton is ahead in the primary.

When Boxer left, she blew kisses at people who approached her to protest what she had said on stage. This is supposedly when her well-being was threatened, but video shows security walking at a normal pace out of the convention space as Boxer snarks at any person angry with her.

The crowd was so unruly after Boxer incited them that convention leaders turned to Sanders surrogate Nina Turner to go out and calm the masses. (She displayed leadership in a moment when she could have responded directly to Boxer and helped make it possible for the convention to continue.)

Sanders is on a path to winning the Democratic presidential primary in California. The Clinton campaign added a significant number of events in California to potentially avert an upset, and even canceled events in New Jersey. The importance of winning California means the campaign will rely on Boxer even more in the final days before the primary.

At what cost? How much more will she alienate independents? How many more Sanders supporters will she push into the camp of “Bernie or Bust”?

The Clinton campaign still sees young Sanders supporters as nothing more than dumb adolescents. It still has surrogates complaining about the inclusiveness of open primaries, which most certainly is a turnoff to independent voters. The campaign seems to believe—as Democrats do every election cycle—that the two-party system will ultimately lead them to support the more reasonable candidate so their votes can be taken for granted.

But there are more people than ever, who are willing to break away from the two-party system, and people like Boxer may be the catalyst for their declaration of independence from settling for the least-worst candidates in presidential elections.