Elon Musk said a new political party he has been threatening to start up “is formed,” a day after President Donald Trump signed a tax-cut and spending bill that the Tesla Inc. billionaire chief executive officer has denounced.

This is Washington’s MO: short-term politicking over long-term sustainability.’ Musk reposted this comment, expressing agreement with a ‘100’ emoji, his first public statement on the bill since its official passage.