At Brandon Johnson’s victory party Tuesday night, Chicago Teacher Union leaders and members hugged and high-fived.

They had plenty to celebrate. All in, the CTU spent an astonishing $2.4 million to get Johnson elected mayor, not to mention the countless hours knocking on doors, making connections, revving up crowds.

Johnson’s win was also a vindication. The union has spent more than a decade fighting the policies of the political establishment and, four years ago, its candidate for mayor, Cook County President Toni Preckwinkle, lost badly in the mayoral runoff. That served as an example to some that the CTU was not all that powerful or popular.

But now, the union faces a profound new challenge: going from agitators to insiders, from the folks on the outside assigning blame to the potential targets of that fire.

In introducing Johnson at the victory party, CTU President Stacy Davis Gates extended an olive branch to entities the union has vigorously opposed — charter schools and police. “Tonight you chose a city where everyone gets a seat,” she declared. “You chose the city where there are charter and public schools. You chose the city where teachers and cops live in the same neighborhood.”

Davis Gates and Johnson both painted a picture of a city under Johnson where everyone gets what they deserve. Johnson told WBEZ on Wednesday that “there doesn’t have to be any losers.”

Other CTU leaders, though, acknowledge the reality of governing will be hard.

Jesse Sharkey, who stepped down as president of the CTU last year, said he doesn’t expect the wealthy Chicagoans who supported Johnson’s opponent, Paul Vallas, will suddenly start helping Johnson. “They’re not going to open their checkbooks and write billion dollar checks because he beat them by 7,000 votes in an election.”

But Johnson might want them to fund some programs, such as making CTA buses and trains free for Chicago Public Schools students, Sharkey said.

Sharkey also thinks the CTU must balance supporting Johnson so he can accomplish his agenda, while also holding him accountable. He noted many progressives were disappointed by President Barack Obama, especially when it came to his education policy.

“So it’s not going to work that we elect someone and then they’re going to go off magically and do what we want,” said Sharkey, who is now a teacher at South Shore International High School. “Our people are gonna have to form connections with people in the neighborhoods, make popular demands in order to make the changes that we want to see happen, and I think that’s our next challenge.”

CTU Vice President Jackson Potter said Johnson and the union are in a good position to get their goals accomplished. They are used to building coalitions and bringing different voices into conversations to reach agreements, he said.

Still, “there’s no shortage of worries. I mean we have got to find revenue to fulfill the promise of fully funded schools, of housing for all, of mental health care, of health care. These are huge, heavy lifts,” Potter said.

Other Johnson supporters see pitfalls to avoid in Mayor Lori Lightfoot’s tenure. Like Johnson, Lightfoot also pledged to make the city more equitable, said Niketa Brar, executive director of Chicago United for Equity. Barr was on Lightfoot’s transition committee. She said there was a lot of hope as they reached out to over 60 groups to come up with a plan.

Lightfoot created equity offices for CPS and the city, which also focused on racial justice. But Barr said the progress didn’t go far enough.

“Equity is something that actually Chicagoans overwhelmingly support,” Barr said. ”But implementing that is a much more difficult task than saying I believe in this. Lightfoot started to make progress on that, but I think it came into conflict with other priorities.”

To make the transition from agitator to governing, Johnson is going to have to confront tradeoffs in each decision, said Sadia Sindhu, executive director of the Center for Effective Government at the University of Chicago.

“To do this successfully, one must move beyond talking points from a campaign and lean in on evidence and expertise,” she said. “There are no silver bullets to the challenges we face.”

Sindhu also notes some ideas Johnson put forth while campaigning might not yield the results he wants. For example, Johnson has proposed reinstating a head tax paid by businesses based on their number of employees, saying it will bring in $20 million. Yet with fewer businesses in Chicago post-pandemic, Sindhu said it will likely yield much less.

Yet Sindhu said Johnson will be held accountable for outcomes. “Four years from now, the conversation will not be about whether we delivered on a specific campaign policy promise, but instead on the intended outcomes — do Chicagoans feel that our children are being set up for educational success? Are our streets safer?” she said.

Despite the challenges, Potter said a Mayor Johnson will make achieving the union’s goals easier. “It is what we hoped for and dreamed for and wished for all along,” he said, “a mayor who could see what it looks like to invest in children and families.”

Sarah Karp covers education for WBEZ. Follow her on Twitter @WBEZeducation and @sskedreporter.