Elon Musk said he’s carrying out his threat to form a new political party after his fissure with President Donald Trump, announcing on social media that he would form the America Party in response to the president’s sweeping tax cuts law.

Trump said third political parties "have never succeeded in the United States" because "the system seems not designed for them."

Americans are entrenched into their partisan corners, but the party lines keep moving in weird new ways. Republicans who grew up in the Grand Old Party might not recognize a party overtaken by the Make America Great Again movement.