Months after her firing as head of the consumer affairs department, Byrne challenged Bilandic in the 1979 Democratic mayoral primary; the real contest in the heavily Democratic Chicago. Officially announcing her mayoral campaign in August 1977, Byrne partnered with Chicago journalist and political consultant Don Rose, who served as her campaign manager. At first, political observers believed her to have little chance of winning. A memorandum inside the Bilandic campaign said it should portray her as, "a shrill, charging, vindictive person—and nothing makes a woman look worse". However, the Chicago Blizzard of 1979 in January paralyzed the city and caused Bilandic to be seen as an ineffective leader. Jesse Jackson endorsed Byrne. Many Republican voters voted in the Democratic primary to beat Bilandic. Infuriated voters in the North Side and Northwest Side retaliated against Bilandic for the Democratic Party's slating of only South Side candidates for the mayor, clerk, and treasurer (the outgoing city clerk, John C. Marcin, was from the Northwest Side). These four factors combined to give Byrne a 51% to 49% victory over Bilandic in the primary. Positioning herself as a reformer, Byrne then won the main election with 82.1% of the vote, still the largest margin in a Chicago mayoral election.