Mr. Musk spent close to $300 million on the 2024 campaign, hosting town halls that drew on his celebrity to try to help Mr. Trump. After the defeat in Wisconsin, Mr. Musk appeared aware that his public presence in the race had backfired, The New York Times reported last year. A few months later, Mr. Musk had a spectacular falling out with Mr. Trump. That summer, Mr. Musk threatened to start a third party, which made some of his advisers who are aligned with the Republican Party skittish. The post Musk Plans at Least $100 Million in Midterm Spending, Giving G.O.P.