From left to right, Geary Yonker, Dave Nayak, Graciela Guzman and Sen. Natalie Toro (D-Chicago) are running in the 20th Senate District Democratic primary.    

It’s one of the most expensive primary races of the year and one that will weigh the influence of a powerful teachers’ union, legislative leader and history of progressive community involvement as four candidates fight for the Democratic nomination in the 20th Senate District on the Northwest Side of Chicago.