CHICAGO — Before Sen. Bernie Sanders (I-Vt.) spoke from the flashy stage of the Democratic National Convention on Tuesday night, he made a decidedly less formal appearance at the city’s unassuming teachers union hall less than a mile away.

The gathering of the Progressive Democrats of America lacked the bright lights and production value of the United Center. But when Sanders took the stage Monday, the small assembly came to life. And the people were largely in lockstep with Sanders in offering their support of Vice President Kamala Harris.

“Kamala, for a variety of reasons, has created a whole lot of excitement and energy. In the next 80 days or something, we have to do everything we can to make sure she wins,” Sanders told the group to cheers.

It was a notable shift in tone for the group that more than eight years ago urged Sanders to run in an effort to push Democrats to the left on economic policy, climate change and international relations.

Progressives have spent the better part of a decade watching Sanders, their favored presidential candidate, lose to more establishment Democrats: first to Hillary Clinton, then to Joe Biden. Still, after failures to move the party at the top of the ticket, many in the Democrats’ left wing have felt at times as if they are winning the ideological war, celebrating gains in Congress and feeling bolstered by President Biden’s embrace of some more liberal priorities. But as Israel’s bombardment in Gaza continues to fracture Democrats broadly, progressives, too, have found themselves wondering how much change they can bring about within the confines of a party apparatus that at times has been reluctant to embrace their ideology.

“A lot of progressives and young people in particular are really energized, especially because it feels like, for the first time in a long, long time, the party responded to the will of its constituents,” said William Walter, a 2020 Sanders delegate who runs Our Wisconsin Revolution, a state affiliate of a Sanders-inspired political action committee.

Progressives felt victorious when Biden and other leading Democrats backed their priorities, including forgiving student loan debt, lowering prescription drug costs, investing in renewable energy and loosening federal restrictions on marijuana. Sanders has said that Biden could be the most progressive president since Franklin D. Roosevelt.

“In large part, we won,” said Joe Caiazzo, an adviser in Sanders’s 2016 and 2020 campaigns.

But others have been disappointed by Biden and Harris, especially over their support of Israel in the ongoing conflict. While some of Sanders’s most ardent supporters, such as Rep. Alexandria Ocasio-Cortez (R-N.Y.), have become darlings to Democrats, others, such as independent presidential candidate Cornel West, once a Sanders supporter, have challenged the Democratic ticket. Ocasio-Cortez got among the warmest responses in the convention hall Monday, while West told reporters outside that the Democratic Party “deserves indictment.”

On Sunday, a Code Pink protester quietly carried a sign around the two-day progressives’ meeting that read “KAMALA: NO WEAPONS TO ISRAEL.” But the next day, audience members carried blue and yellow fans distributed by the United Food & Commercial Workers International Union that read “2024 HARRIS WALZ.”

One of the most motivating factors for progressives is a concern about a second term of former president Donald Trump. Speakers at the progressives’ gathering — including Congressional Progressive Caucus Chair Rep. Pramila Jayapal (D-Wash.), Rep. Ro Khanna (D-Calif.) and Rep. Maxwell Frost (D-Fla.) — emphasized the stakes of the election, painting a grim picture of the Republican ticket that would retreat from more liberal policies, such as raising the minimum wage, broadening social safety net programs and welcoming immigrants.

Khanna said that, although he may disagree with the leaders of his party on some issues, in particular the situation in Gaza, he understands the bigger threat to progressives would be if Trump returned to office.

“The Bernie movement recognizes the stakes of the election and are supporting the Harris-Walz ticket,” he told The Washington Post.

Several progressives stressed that Biden’s stepping aside, Harris’s rise to the top and her choice for Walz were signs of forward momentum for them. They had lobbied Harris to pick Walz, who many saw as a popular Midwestern governor who has successfully shepherded liberal policies in Minnesota and who could be a possible sympathetic ear in a Harris White House.

The political action committee Our Revolution, which rose out of Sanders’s 2016 campaign, celebrated the Walz pick as “great news for progressives,” saying it would try to devote more than $1 million to turning out voters in battleground states.

Others see opportunities to negotiate with Harris. Asked about her moderating her views recently, including backing away from her previous support for Medicare-for-all and for banning fracking, some progressives waved off concerns. They pointed to her support of Medicare-for-all when she was a senator and her seeming openness to listening, such as when she met briefly with leaders of the Uncommitted movement concerned about the war in Gaza on a photo line during a Michigan trip earlier this month. Her campaign has also engaged regularly with organizers.

Jayapal said she expects Harris as president could go after corporations more than Biden has. She said that, “while perfection is rarely on the ballot, real progress is.”

“People do feel like there’s a little bit more room to talk to her, particularly on the Gaza war,” Jayapal said.

Still, Nina Turner, a co-chair of Sanders’s 2020 campaign, said that Sanders’s movement “seems a little scattered,” pointing to dissent over Israel. Her call for progressives to push Harris toward an arms embargo and cease-fire garnered the loudest applause of the progressive convention’s first day.

“I do have a fear that if the Harris-Walz team does not take what’s happening in Gaza seriously, they could still lose,” she said in an interview.

Turner said she was uncertain, albeit hopeful, about whether Harris could be a trusted partner with the movement. When Turner spoke with the Teamsters National Black Caucus, which endorsed Harris, while the broader union has so far withheld its endorsement, Turner warned the group to be unrelenting in its pushing Harris and to not accept platitudes.

Liano Sharon, a Michigan delegate who helped unfurl the “STOP ARMING ISRAEL” sign at the convention Monday, said he was first inspired to join the Democratic Party because of Sanders’s message in 2016 to progressives to take over the party. He has been repeatedly disappointed by Democrats, including when those in the hall tore away his sign. And he has been distrustful of the Biden White House’s promises that it will stop the conflict in Israel.

Because of that, he voted “uncommitted” during the primary. But he said he will vote for Harris in the general. To him, he’s not really voting for Harris.

“My general election vote is against Donald Trump,” he said.

Alan Minsky, executive director of the Progressive Democrats of America, agreed that Gaza remains a major concern for those skeptical of the Democratic ticket in his wing of the party. Meanwhile, he said that those once spurred by the DNC had moved on.

After he had brought in a slew of Democratic lawmakers and figureheads to speak at his group’s event, he concluded that there was little animosity between his cohort and the establishment Democrats filing into the convention hall less than a mile away.

“We’re big kids. We’re not crying about it,” he said. “Onward.”