Among the Democrats to decline to run for the nomination were Treasurer (and former Republican) Barbara Hafer, Public Utilities Commissioner John Hanger, real estate mogul Howard Hanna, State Representative (and also former Republican) John Lawless, and State Senator (and future Congresswoman) Allyson Schwartz.

[3] Although Specter had a huge fundraising advantage, Toomey was aided by $2 million of advertising from the Club for Growth, a conservative political action committee that focuses on fiscal issues and targets moderate Republican incumbents.

Although Toomey had difficulty with name recognition early in the campaign, he built huge momentum over the final weeks preceding the primary, and Specter appeared to have transitioned from having a comfortable lead to being behind his challenger.

Many Republicans at the state and national level feared that if Toomey beat Specter, he wouldn't be able to defend the seat against his Democratic opponent.

However, after the challenge from the right failed, enthusiasm from the party establishment waned and Hoeffel had difficulty matching the name recognition and fundraising power of his opponent [22] Despite contempt from conservatives, Specter enjoyed high levels of support from independent voters and, as in previous elections, a surprisingly large crossover from Democratic voters.