Donald Trump has congratulated Boris Johnson on his "great win" and said the UK and US were “now free to strike a massive new trade deal after Brexit”.
The US President said the agreement had the potential to be "far bigger and more lucrative" than any deal which could have been made with the European Union.
It came after it was confirmed that the Conservative Party had secured a majority in the general election.
Mr Trump had earlier tweeted to say that it was "looking like" Mr Johnson was on course for a "big win".
Hours later, after the Tories passed the required threshold of 326 seats, he wrote: "Congratulations to Boris Johnson on his great WIN! Britain and the United States will now be free to strike a massive new Trade Deal after BREXIT.
"This deal has the potential to be far bigger and more lucrative than any deal that could be made with the E.U. Celebrate Boris!"
The prospect of a trade deal with the US was a major talking point during the election campaign, with Labour claiming the NHS was at risk of being sold off to US companies in the fallout from Brexit.
Those accusations were denied by both sides, with Mr Trump telling journalists during his recent visit to Britain for the Nato summit that he wants "nothing to do with" the health service.
He added that he had "never even thought about it", despite stating during a previous visit that "when you're dealing in trade, everything is on the table".
The PM and President have a chequered history, with Mr Johnson once joking that he would avoid some parts of New York because of the "real risk" of meeting him.
Last week he was filmed laughing as Canadian PM Justin Trudeau and French President Emmanuel Macron appeared to discuss Mr Trump's bombastic arrival in the UK.
Nonetheless, Mr Trump has consistently offered his support to Mr Johnson since taking up the Presidency, telling the Sun last year that he would make a "great" Prime Minister, even though Theresa May was still in the role at the time.
