It began with Musk complaining about the centerpiece of Trump’s legislative agenda, which the president at first took in stride. Eventually Trump let slip that he was disappointed in his former adviser, prompting Musk to unleash a flood of insults and taunts.

A knock-down fight between world's the richest person and the most powerful politician is playing out in public view.

Remaking Government, your guide to Donald Trump’s unprecedented overhaul of the federal government — the key decisions, the critical characters and the power dynamics that are upending Washington and beyond.