25 Pa. Stat. § 3377
Upon the petition in writing, as hereinafter provided, of at least fifty (50) registered electors of the district for which the person whose nomination or election is contested was returned as nominated or elected, presented to the Governor of the Commonwealth, complaining of an illegal primary or election or false return of any judge of a court of any judicial district of the Commonwealth the Governor shall without delay, direct the three president judges residing nearest to the courthouse of the county composing the district, or, if more than one county composes the judicial district, then those nearest the courthouse of the most populous county of the district, to convene without delay the court of common pleas of such county, and proceed to hear and determine the complaint of the said petition.
25 P.S. § 3377