President Donald Trump and billionaire Elon Musk’s alliance ended dramatically this week as the two publicly feuded on social media over Republican lawmakers’ One Big Beautiful Bill Act, which would advance the president’s agenda.

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.