HARRISBURG, Pa. (AP) — Sensing a threat in Pennsylvania’s U.S. Senate race, Donald Trump has issued a warning that surging Republican candidate Kathy Barnette would upend the GOP’s chances of holding the seat in November. He is urging voters to back his pick, TV’s Dr. Mehmet Oz. Trump said Thursday that only Oz can win the fall election against the Democratic nominee. The former president’s statement echoed growing panic among his allies and the party establishment over Barnette’s sudden and unforeseen rise ahead of the state’s May 17 primary. Pennsylvania’s Republican Senate primary had been primarily an expensive duel between Oz and former hedge fund CEO David McCormick.