Incumbent Republican mayor Rudy Giuliani could not run again due to term limits. As Democrats outnumbered Republicans by a five-to-one margin in the city, it was widely believed that a Democrat would succeed him in City Hall. Businessman Michael Bloomberg, a lifelong Democrat, changed his party affiliation and ran as a Republican. Mark J. Green narrowly defeated Fernando Ferrer in the Democratic primary, surviving a negative contest that divided the party and consumed the vast majority of the Green campaign's financial resources. After a campaign that was largely overshadowed by the 9/11 terrorist attacks, Bloomberg won the general election with 50.3% of the vote to Green's 47.9%.