Thousands of Brandon Johnson supporters packed an arena at the University of Illinois at Chicago Thursday night where longtime Sen. Bernie Sanders, the darling of the political left, cast Tuesday’s mayoral runoff as a choice between the interests of the “powerful and greedy” and “the son of the working class.”

The two-time Democratic presidential stressed the importance of voter turnout and decried the “establishment” that he said was stifling a movement sparked by Johnson, the progressive Cook County commissioner vying for Chicago mayor against former Chicago Public Schools CEO Paul Vallas.

“Now, Brandon’s opponent and on the other side, they have a lot of money,” Sanders said, pointing his finger. “And that’s what always happens when you take over the establishment. They have a lot of power. But you know what we have? We have the people.”

Sanders then ripped what he said was the “greed of real estate speculators and Wall Street” as he painted a picture of widening income inequality across the “richest country in the history of the world.”

“All of us today, in an unprecedented way, we are seeing the rich get richer while the working class struggles to stay alive,” Sanders said. “And what this campaign in Chicago is about is bringing the working class together.”

While Johnson topped other progressives to win his place in the runoff, Vallas has also touted the endorsements of dozens of labors unions, along with prominent Black and Latino political, community and faith leaders. He repeatedly refers to himself as a “lifelong Democrat” to blunt criticisms and past comments that suggest he’s too far right for Chicago, while with his crime-focused campaign, he’s also picked up support from those who view Johnson as too far left.

At the rally, Sanders argued Johnson is the candidate who would reverse that cavernous disparity through his advocacy of public education, union-backed job creation, health care and “smart” solutions to the gun violence epidemic.

“We must address that crisis,” Sanders said about Chicago’s high crime. “But we must do it in a way that is smart and effective, and that means not only high quality and non-racist law enforcement, it means that we must address the epidemic of mental illness, the epidemic of drug abuse, the epidemic of poverty and the epidemic of guns on the street. And that is something that Brandon Johnson understands.”

Sanders concluded with one last jab at the rich, a signature message of his presidential runs and beyond.

“I have absolute confidence that we stand together, if we have the courage to take on powerful people whose greed is destroying us — if we are prepared to do that, we can create the kind of city that the people of Chicago deserve, the kind of nation that all of us deserve,” Sanders said.

He concluded: “The fundamental issue, the deep down issue, is: Which side are you on? Are you on the side of working people? Or are you on the side of the speculators and the billionaires? And I know which side Brandon is on.”

Johnson then strode on stage, clasping his hands with Sanders and raising them above their heads as the crowd roared. He with one of his jokes that have become part and parcel to his speeches.

“I think that’s someone that tried to date me in high school,” he said in response to an especially loud holler. “It’s too late, sister.”

The candidate then picked up where the senator left off by discussing the makeup of Vallas’ biggest financial backers.

“Now they are some forces, however, that are intimidated by this room,” he said. “I mean they are so intimidated that they have thrown everything imaginable at this brother here.”

But he reminded the audience — many donning Chicago Teachers Union and Service Employees International Union sweatshirts — that his loyalty is with them: “Last I checked, Chicago is a union town. If you are an enemy of labor, you are an enemy of the people.”

Johnson sought to connect the antipathy Vallas and his supporters have wielded against CTU leadership to the plight of Black people.

“Keep in mind: these are the same enemies of one of the greatest humanitarians to walk the earth: The Rev. Martin Luther King Jr.,” Johnson said. “He said the enemy of labor is the enemy of the Negro. Those are his words.”

Johnson also made pointed critiques of Vallas, ones that elicited loud boos and hisses from the audience that vigorously waved his blue campaign signs.”His failures are so profound we are still living the experience of his failures,” Johnson said before alluding to how some of his opponents’ donors also gave money to former Republican President Donald Trump.

”When you take dollars from Trump supporters and try to cast yourself as a part of the progressive movement, man — sit down,” Johnson said. “… Those forces that have wrapped themselves up in my opponent, they want to redo the mess that they created.”

Earlier, Randi Weingarten, the president of the American Federation of Teachers, praised Johnson’s decade of work as an organizer for the Chicago Teachers Union before turning her attention toward opponent Paul Vallas’ record leading public school districts in Chicago and other cities.

“Can there be any better indicator where Paul Vallas stands than for Betsy DeVos?” Weingarten said, to the audience’s boos. “For Betsy DeVos and her (political action committee) to come in and support Paul Vallas tells you everything you need to know about him. We need uniters, not dividers, in Chicago.”

DeVos has not donated directly to Vallas, but an advocacy organization she founded channeled money into a super PAC called Illinois Federation for Children that spent roughly $60,000 on digital media supporting Vallas, state election records show. She has not led the group since 2016, but she and her husband continue to contribute to the group.

The Vallas campaign said in a Thursday statement that he would “strongly reject” any endorsement from her and noted the firewall between such himself and any independent political committees, which he is not allowed to coordinate with.

Vallas also released a statement in support of the reported indictment of Trump, which was not directly addressed during the Sanders’ rally.

“Donald Trump repeatedly and shamelessly violated the rules and norms that govern the Office of the President, cheapening the most widely respected elected position in the world and demeaning our democracy,” Vallas’ statement read. “He must be held accountable and I’m grateful the first step towards justice has been taken.”

Also at Thursday’s rally, Martin Luther King III, the son of the slain civil rights legend, took to the stage to echo a message that the candidate has been repeating on the campaign trail.

“My father used to say that one of the most important steps that we need to take is the steps to the ballot box,” King said. “April 4th will be 55 years since my father was killed, but he is going to be looking down on Chicago on Tuesday.”

King then went on to condemn groups who have supported Johnson’s opponent, including the Chicago Fraternal Order of Police President John Catanzara.

“I mean it’s just totally irresponsible to talk about some blood occurring in the streets because someone is elected to office,” the activist said in reference to comments Catanzara made in which he warned there would be “blood in the streets” from cops quitting en masse under a Johnson administration. “That is some sick mentality, and we cannot continue to embrace and support that kind of leadership.”

Vallas condemned the Catanzara comment.

As Johnson continued his speech, he pointed out two former students in the standing pit: “They still owe me some assignments, but I told them since they are voting for me, I’ll excuse it.”

Toward the end, the candidate led the crowd in a chant: “Paul Vallas, take a seat.”

“Don’t that feel real good?” Johnson asked afterward.

The Tribune’s A.D. Quig contributed.