HARRISBURG (AP) – A Republican state lawmaker says he will not challenge Democrat U.S. Sen. Bob Casey for his post. The decision leaves the GOP primary field wide open. Sen. Doug Mastriano, who represents Adams & Franklin Counties, made the announcement Thursday night as top party officials try to recruit a strong candidate for the U.S. Senate race in 2024. Casey announced that he will seek a fourth term in office. Former hedge fund CEO David McCormick is the favorite of GOP party leaders and has drawn pledges of financial support from top Republican officials should he decide to run. Mastriano was endorsed by former President Donald Trump in last year’s race for PA governor, but lost to Democrat Josh Shapiro. The Keystone State is a top GOP target in their quest to recapture the U.S. Senate majority.