CHICAGO — Ex-House speaker Michael Madigan, formerly the most powerful man in Illinois politics, “conspired to enhance and preserve (his) power and line his pockets” for years, prosecutors said at the outset of marathon closing arguments in Madigan’s corruption trial.

Madigan, 82, and his co-defendant, political ally and confidant Michael McClain, are accused of running a criminal enterprise designed to enrich the former speaker and his associates and increase his political power.

Prosecutors concluded their final summations Friday on Day 3 of closing arguments in the former speaker’s landmark trial by presenting an overview of how the various bribery and corruption schemes alleged in the government’s 23-charge indictment all come together under count one: racketeering conspiracy.