A massive Republican primary field for governor in Pennsylvania is spurring growing discomfort among party leaders that a widely splintered primary vote could produce a winner who cannot beat Democrat Josh Shapiro in November’s general election. Ten Republicans filed paperwork Tuesday to get on the May 17 primary ballot. That is more than party leaders expected or have ever seen in such a high-profile primary contest. It prompted grumbling over the state party’s decision not to endorse in a gubernatorial primary for the first time since 1978. It has also propelled party leaders to begin working on a strategy to persuade some candidates who are perceived as weaker to drop out. They worry that a weak or polarizing candidate could theoretically win the primary election with less than 20% of the vote.