The Chicago Democrat had been widely expected to win another four years in the job she's held since 2002. She easily won her last two elections, had raised millions and built a national profile by playing a key role in multi-state lawsuits. Many had expected her to run for governor, but in July she announced she would seek re-election instead.
Schimpf of Waterloo is a prosecutor and U.S. Naval Academy graduate. He focused on promises to fight corruption.
Madigan is known for a 2012 settlement she helped negotiate with mortgage lenders over fraudulent practices after the housing bubble burst. Her office also has investigated for-profit colleges that allegedly left students unqualified for jobs.