Sandoval, 55, has served in the Senate since 2003, representing a district on Chicago's southwest side. He is chairman of the powerful Transportation Committee and was a driving force behind an 18-cent increase in the gas tax to help fund Democratic Gov. J.B. Pritzker's $45 billion capital construction plan to rebuild roads, bridges and schools.
Republicans criticized him in August when a photo from a fundraiser appeared on social media showing what appeared to be a mock assassination of President Donald Trump. Sandoval later said neither he nor his staff was aware that an entertainment vendor had a beverage dispenser shaped like a rifle and pointed it at someone wearing a Trump mask. He expressed "my deepest regret that this unfortunate incident took place at (an) event in my name."