The Pennsylvania Rules

In spite of its vote-rich battleground status, Pennsylvania has been home to only one president, the little-known James Buchanan, and has not offered a significant presidential candidate since 1964, when then-governor William Scranton mounted an unsuccessful eleventh-hour bid against Barry Goldwater for the Republican nomination.

Nor has Pennsylvania's presidential primary been of much import in recent years, in large part because the state has decided not to change its traditional spring primary date. Pennsylvania will be the last of the nation's most populous states (those with 20 or more electoral votes) to hold its primary or caucus in 2008.

Democrats use the presidential preference part of the ballot to allocate delegates. For Republicans, though, it is a nonbinding "beauty contest." the votes that really count are those for district delegates, who are elected separately on the GOP primary ballot without their candidate preference listed. At-large delegates are elected by the Republican state committee at a post-primary meeting in June. All Republican delegates are formally uncommitted.

Participation in the primary is limited to registered voters in each party. As of May 2007, there were 8,107,433 registered voters in Pennsylvania—3,872,018 Democrats, 3,259,243 Republicans, and 976,172 other voters.