OKLAHOMA CITY (AP) — The number of Republicans seeking to unseat U.S. Rep. Kendra Horn, the lone Democrat in Oklahoma’s congressional delegation, is continuing to grow.

Former State Superintendent of Public Instruction Janet Barresi and Edmond businessman David Hill both announced this week they plan to seek the GOP nomination for the 5th District seat. Hill owns and operates MAR-K, an automobile parts manufacturing company.

They join five other Republicans who have filed campaign paperwork with the Federal Election Commission indicating their plans to run. Candidates won’t officially file for...