President Donald Trump posted a video attacking Sen.
Trump was upset over Romney's decision to vote in favor of convicting him of abuse of power on Wednesday.
Romney was the only GOP senator to go against Trump.
Trump acquitted of both impeachment charges he faced.
The video posted by Trump included footage of Romney praising Trump and failing to win the 2012 presidential election.
"Corrupting an election to keep oneself in office is perhaps the most abusive and destructive violation of one's oath of office that I can imagine," Romney said in a speech explaining his decision.