The Democratic Party primary campaign saw two well-known, well-funded Philadelphia congressmen – Bob Brady and Chaka Fattah – eclipsed by self-funding businessman Tom Knox and reformist former Philadelphia City Council member Nutter, who won by a surprisingly large margin in the primary election on May 15.

Nearly four out of five Philadelphia voters are registered Democrats and the city has not elected a Republican mayor in close to sixty years.

[4] Philadelphia City Council member Michael Nutter won the Democratic mayoral primary on May 15.

His opponent, businessman Tom Knox came in second, with congressmen Bob Brady and Chaka Fattah and State Representative Dwight Evans coming in third, fourth, and fifth respectively.

[3] Businessman Tom Knox had started off strong as his self-financed campaign created a barrage of advertising.

However, Nutter's message of government reform and criticism of mayor Street gained him enough support to win the primary.

[3] On November 6, Michael Nutter easily won the mayoral election, receiving 83.4% of the vote to Taubenberger's 17.3%.