Attorney General Mike Fisher ran unopposed for the Republican nomination. Although incumbent Governor Mark Schweiker was eligible to run for reelection (he had served only a partial term after Tom Ridge resigned to become Homeland Security Advisor), he chose not to seek his party's nomination. Despite polls showing that Schweiker polled well among the same groups that backed Ridge, the Republican establishment considered Schweiker to be a weak candidate and stood steadfast behind Fisher.
In the Democratic primary, former Mayor of Philadelphia Ed Rendell defeated Pennsylvania Auditor General Bob Casey Jr., bucking the "myth that a Philadelphian could never win" a statewide election. Despite strong support from organized labor for Casey, lackluster campaigning combined with Rendell's ability to cast himself as a strong executive allowed him to pull out a primary win.
Democratic primary results by county
Rendell defeated Fisher with "endless retail politicking" and a hard-working campaign. The political website PoliticsPA praised Rendell's campaign team of David L. Cohen, David W. Sweet, and Sandi Vito.
Rendell was the first official from Philadelphia to win a spot in the governor's mansion since 1914. Although Fisher emphasized Rendell's Philadelphia roots continuously during his campaign, and described the mayor as an urban liberal whose programs would require huge tax increases, his strategy backfired; in much of Eastern Pennsylvania, voters instead related to Rendell, and he was thus able to win by huge margins in even many traditionally GOP suburbs.