PITTSBURGH — Just days before Pennsylvania’s primary elections, the Republican Senate nomination has been turned upside down with a late surge from Kathy Barnette, a virtual unknown whose sudden rise has riled former President Donald Trump and his allies.

Multiple polls this week have shown Barnette within striking distance for the nomination to replace retiring GOP Sen. Pat Toomey. She’s a conservative commentator who moved to the state about eight years ago and failed in a bid for a Philadelphia-area House seat in 2020. She lost the safe Democratic seat by 20 points, a result she blamed on voter fraud.

Although Barnette has spent a fraction of her rivals' outlay on television ads, a confluence of events — late endorsements, an alliance with the gubernatorial frontrunner, a lack of enthusiasm for other options and a viral ad about her own mother’s decision not to have an abortion after being raped at age 11 — has pushed her into contention.