President Trump’s decision to pull a close associate of Elon Musk’s out of the running to lead NASA helped doom an extraordinary partnership.

The falling-out between Elon Musk and President Trump went into overdrive on Thursday. Both men have powerful ways to keep it going.

The sudden fallout ended a nearly yearlong partnership, during which Mr. Musk helped propel Mr. Trump to the White House and became one of the president’s top advisers.