With far-right state Sen. Doug Mastriano on the verge of capturing the Pennsylvania GOP gubernatorial nomination, Republicans are lashing out, furious that he could cost them a shot at a competitive race in the perennial swing state. Last-ditch efforts to stop Mastriano seemed doomed from the start. But the final blow likely came on Saturday, when former President Donald Trump threw his support behind Mastriano, who has been one of the chief boosters of conspiracy theories about the 2020 election and was also at the Capitol on Jan. 6.