The New York City mayoral election of 2001 was held on November 6, 2001. 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%.