PHILADELPHIA ― The first night of the Democratic National Convention in Philadelphia was supposed to be a show of unity ― a moment when Hillary Clinton, the party’s presidential nominee, and Bernie Sanders, her primary rival, could bring their supporters together to defeat Republican nominee Donald Trump. “Our convention could not be a greater contrast to the Republicans’ last week,” Robby Mook, Clinton’s campaign manager, promised Monday morning. “One of [Trump’s primary] opponents wouldn’t even endorse him!”

But unity was not in evidence at the opening day of the DNC, as angry and frustrated Sanders supporters inside the Wells Fargo Center and in the streets of Philadelphia denounced Hillary Clinton and vowed to never support her candidacy. Sanders, who has endorsed Clinton, texted some of his delegates on Monday afternoon urging them not to protest on the convention floor. But from the first moments of the convention broadcast, some Sanders delegates ― especially those from the restive California delegation ― chanted his name and booed mentions of Clinton. The vote on the official Democratic Party platform included a loud “no” vote. When Rep. Elijah Cummings (D-Md.) spoke about Black Lives Matter and his late father, some delegates chanted “No TPP” — a reference to the Trans-Pacific Partnership, a trade deal Sanders opposes.

A “Bernie! Bernie! Bernie!” chant ― and some boos ― even broke out during the convention’s opening prayer.

At a breakfast earlier in the day for California’s delegation, House Minority Leader Nancy Pelosi and progressive stalwarts like Rep. Mike Honda and Barbara Lee were drowned out by chants of Sanders’ name and boos each time Clinton or her running mate, Virginia Sen. Tim Kaine, was mentioned.

Some Sanders delegates hinted that such disruptions would be commonplace in Philadelphia this week. And so far, even Sanders himself can’t get the dissenters to back Clinton: When the senator urged a meeting of the Vermont delegation to vote for Clinton in the general election, they booed him.

Rep. Debbie Wasserman Schultz (D-Fla.) left Philadelphia before the official beginning of the convention on Monday, after being forced out of her job as DNC Chair. Wasserman Schultz had been deeply unpopular with Sanders supporters for months, and Sanders himself called for her resignation months ago after several actions by the officially neutral party appeared to favor the campaign of Hillary Clinton. That unrest was inflamed over the weekend after WikiLeaks released over 20,000 internal DNC emails that showed top party aides and officials plotting against Sanders.

But ousting DWS, as she is known among party insiders, did not mollify frustrated Sanders backers. As Rep. Marcia Fudge (D-Ohio) was named Chair of the 2016 Convention, her speech was overpowered by boos and chants of “Bernie! Bernie!”

“Excuse me, excuse me,” Fudge said, trying to calm the raucous arena. “May I just make a point,” Fudge said. “There are many of you that do not know me in this room. Let me say to you, I want to be fair … I want to be respectful of you, and I want you to be respectful of me. We are all Democrats and we need to act like it.”

Anti-Clinton protests were no less heated outside the arena walls. As delegates entered the convention center, hundreds of Bernie backers jeered from beyond the fence. Police had to help delegates enter. In the morning, hundreds of other supporters gathered outside the Philadelphia convention center, chanting, “Hell no, DNC, we won’t vote for Hillary!”

Democratic Ohio state Sen. Nina Turner, a top Sanders surrogate during the campaign, was one of several speakers to address the crowd. But while Turner praised the energy and enthusiasm of those gathered, she stopped short of imploring them to vote for Clinton in the fall.

“I’m not gonna be that Democrat that asks you to vote in an atmosphere of fear,” Turner said. “But we all do have to search our hearts and decide what kind of country we want to live in and who is best at this moment to get us there. So I am never going to tell you, or dictate to you, or preach down to you. Because I feel your pain, I understand where you’re coming from, and more Democrats need to respect the feelings of the supporters of Bernie Sanders.”

Even Huffington Post’s Sam Stein, a prominent cable news personality, wasn’t spared Sanders supporters’ ire. “Sam Stein, you fucking traitor!” one protester jeered at him as he passed through a crowd of Sanders supporters on his way to the arena.

The divisions in the Democratic party may not be as severe as the first hours of the convention suggested. Big news events like conventions can highlight louder voices ― even if those voices don’t represent majority opinions. One recent survey by Pew found that around 90 percent of voters who consistently supported Sanders throughout the primary favor Clinton over Trump in the general election. But other data ― and the chaos Monday ― suggest the former secretary of state might have a tough time convincing many Sanders supporters to vote for her. FiveThirtyEight has estimated that about a third of Sanders supporters aren’t ready to vote for Clinton ― and that around a fifth of them will vote for a third-party candidate like libertarian Gary Johnson or Green Party candidate Jill Stein. That’s in part because many Sanders supporters were never loyal Democrats. “Before the 2016 primaries, Sanders’s supporters voted less frequently than other 2016 voters, and they were less reliably Democratic than Clinton supporters,” FiveThirtyEight reported Monday.

Some Sanders delegates are still planning to walk out of Clinton’s speech on Thursday ― a dramatic gesture that the Clinton campaign would no doubt like to prevent. But even a request from Sanders himself won’t necessarily prevent the walkout from happening, Norman Solomon, a California Sanders delegate and coordinator of the Bernie Delegates Network, said at a press conference Monday.

“If we’re asked by Bernie, don’t do this, then we’ll take that under advisement as we would from any other source,” Solomon said. “But we take very seriously what Bernie enunciated throughout the campaign ― social change that’s worth a damn always comes from the grassroots.”

Solomon and other delegates who spoke at the Bernie Delegates Network press conference made it clear that their goal for the convention was not unity, but further pushing the Sanders wing’s goals, even if the senator himself was no longer on board.

“He’s not running the show,” said Solomon. “He’s not running the social movements. It’s activists.”