President Donald Trump derided billionaire Tom Steyer as a "wacky" and "crazed & stumbling lunatic" in a tweet Sunday, just days after the Democratic activist was one of the prominent liberals and Trump critics to be sent a suspicious package.

Why it matters: Trump’s tweet came in response to Steyer’s interview on CNN, in which he said the president and the Republican Party are creating a climate of "political violence." On Friday, Steyer called for the president's impeachment citing "a systematic attack on our democracy that extends much further than just one isolated terrorist in Florida."