What started as a volley of barbs snowballed into a feud involving multiple social platforms and millions of onlookers, as everyone from big-name politicians to no-name meme accounts hurried to offer their takes and declare their allegiances.

An intense public feud erupted on Thursday between President Donald Trump and his one-time ally, billionaire Elon Musk, with an argument about Trump’s massive tax and domestic policy bill raging across social media and in the Oval Office.