The next item on Mayor Brandon Johnson’s progressive agenda: A new Bears stadium. Will his coalition embrace it?

Chicago’s progressive movement has long championed social justice interests, from good government advocates to labor rabble-rousers, police abolitionists and public education reformers.

Now, Mayor Brandon Johnson hopes to shoehorn a wealthy new group into the fold: the Chicago Bears.

During a long-awaited presentation at Soldier Field Wednesday, the mayor stood with the National Football League franchise’s CEO and President Kevin Warren to debut a nearly $5 billion proposal for a...