McCall Cullen, often called Mac, is the incumbent Governor of Illinois. He is serving his fourth and final term, having lost his party's nomination to run for re-election to State Treasurer Ben Zajac.Season 1Mayor of Chicago Tom Kane speaks in support of Governor Cullen for re-election at a campaign event. Kane then backs away from his crony to support young and ambitious state treasurer Ben Zajac to replace Cullen. He takes Zajac to the City Hall roof gardens, ensuring that their meeting is publicized and sending a message to Cullen.[from Listen episode]Season 2Zajac calls him for advice about campaigning against rival gubernatorial nominee Senator Catherine Walsh, who Mac has defeated in the past. Mac relishes Zajac's apology for the primary and then tells him to eat shit. [from Louder than Words]McCall Cullen is a recurring character in the first and second seasons. He is played by guest star Francis Guinan.