John Paulson, the billionaire investor who has been close to Mr. Trump for more than a decade, said he would work with Mr. Musk to slash federal spending if Mr. Trump were elected president and he became Treasury secretary in his second term. Mr. Paulson said in an interview that his first priority would be to extend the expiring tax cuts Mr. Trump enacted in 2017, followed by "working with Mr. Musk to cut federal spending", particularly by eliminating green energy subsidies in the Inflation Cuts Act. Mr. Paulson, 68, has been close to Mr. Trump for more than a decade and is one of several candidates considered by Mr. Trump and his allies for the job, according to people familiar with the matter.