"I actually have studied it very hard. I know the different players," Trump said in an interview published on Friday by UK media outlet The Sun. "But I think Boris would do a very good job. I think he would be excellent."
The US president also praised current UK Foreign Affairs Secretary Jeremy Hunt for pledging to increase UK defence spending above the two percent minimum set for NATO member states if he becomes prime minister.
Last week, UK Prime Minister Theresa May announced she would resign as the leader of the party on June 7 and remain prime minister until a new one was elected. Her resignation came amid pressure from within the party and continuing deadlock over the EU withdrawal agreement, rejected by the UK parliament three times.