Elon Musk’s bitter falling-out with President Trump could be costly for Tesla. As long as he is persona non grata in the Trump administration, Mr. Musk, the chief executive of Tesla, will struggle to persuade Republicans not to gut climate policies worth billions of dollars to the electric car and battery company.

The billionaire’s feud with the president over the nation’s debt is jeopardizing lucrative deals for SpaceX and other Musk companies.