On Tuesday night, the tectonic plates bracing Chicago politics tilted dramatically. Brandon Johnson, a former rank-and-file member of and staff organizer for the Chicago Teachers Union (CTU), secured a spot in the runoff race for mayor, where he will face conservative privatizer Paul Vallas on April 4.

Outperforming both incumbent mayor Lori Lightfoot and Representative Jesús “Chuy” García, Johnson pulled off a shocking upset. He ran an unapologetic left-wing campaign that prioritized taxing the rich to fund social programs and reimagining public safety to increase investments in mental health and other city services. At his victory party last night, Johnson announced, “The finances of this city belong to the people of the city. So we’re gonna invest in the people of the city.”

Johnson, who now serves as an elected member of the Cook County Board, started the race with little name recognition and faced eight challengers. Just a month ago, Lightfoot scoffed at Johnson’s candidacy, claiming that he “is not going to make the runoff” and “isn’t going to be mayor of this city.”