PHOENIX (AP) — Blake Masters has formally launched his campaign for the Republican nomination to challenge Democratic Sen. Mark Kelly. Masters is a longtime executive for the firm run by billionaire investor Peter Thiel. He grew up in Tucson and moved back to southern Arizona in 2018. Masters kicked off his first run for political office Monday with a video showcasing his wife and three young boys. He says America needs to finish the border wall, enforce the law and build an economy where families can live on a single income. Masters joins a crowded field of Republicans looking to take on Kelly in one of the top-tier U.S. Senate races of 2022.