HARRISBURG, Pa. (AP) - Pennsylvania is in the minority of states with closed primary elections, but the fast-growing number of independent voters is sparking a debate in Pennsylvania's Legislature about opening up party primaries.
  
It helps that it is led by a high-profile backer, the top Republican in the GOP-controlled state Senate, Joe Scarnati.
  
Scarnati says allowing independent voters to cast ballots in party primaries can curb extremism in primary elections and increase voter turnout.
  
Scarnati's bill has the support of the Senate's ranking Democrat, Jay Costa, and Gov. Tom Wolf.
  
In Pennsylvania, the number of unaffiliated voters has grown 75% in eight years, a reflection of national trends.
  
Here's the catch: researchers don't find that open primaries have much, if any, effect on increasing turnout or moderating politics.

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