If an elector in districts other than in cities of the first, second, and third classes, enrolled as a member of a party, is challenged at the primaries as to his party enrollment, he shall make oath before the election officers, that at the last preceding November election at which he voted, he voted for a majority of the candidates of that party: Provided, however, That the group of Presidential electors shall be counted as two candidates.
25 P.S.§ 296