How Trump-backed candidates fared on the busiest primary day

Donald Trump’s preoccupation with his endorsement win-loss record was never more apparent than in Pennsylvania.

The former president endorsed state Sen. Doug Mastriano for governor in the final week before the Republican primary, despite the efforts of state Republicans to convince him otherwise. As a leading election denier who worked vigorously to overturn the 2020 election results, Mastriano was a natural for Trump to choose. He was also a high-risk nominee, one whom many in the party believe will get crushed in November.

Trump knew this and endorsed him anyway, leading...