The list of people Donald Trump has punished or threatened to punish since returning to office is long. It includes the likes of James Comey, Letitia James, John Bolton, as well as members of the opposition, such as Adam Schiff, Mark Kelly and Kamala Harris.

In fact, he has gone so far as to call Democrats "the enemy from within", saying they are more dangerous than US adversaries like Russia and China.

According to Lucan Way, a professor of democracy at the University of Toronto, when a leader attacks the opposition like this, it's a clear sign a country is slipping into authoritarianism.