David Cameron has insisted Britain's special relationship with the USA will work regardless of who is president, as Donald Trump finally secured the number of delegates he needs to claim the Republican nomination.
Asked whether he would like to congratulate Mr Trump on passing the crucial milestone, the Prime Minister said he would congratulate anyone who completed the arduous process of securing a presidential nomination, but steered well clear of anything that could be interpreted as an endorsement of the property tycoon's candidacy.
He insisted he was "not going to get involved" in the US contest. which he said "is obviously going to be a very interesting election for us all to watch".
Mr Cameron said he would be happy to meet Mr Trump if the presidential hopeful came to London during the campaign, but added that no visit has yet been fixed.
The Prime Minister is set for an awkward first meeting with the businessman and reality TV star, who said he might not have a "very good relationship" with Mr Cameron after the PM described his proposal to exclude Muslims from entering the US as "stupid, divisive and wrong".
The comment was made in the House of Commons at a time when Mr Trump seemed an outsider in the race for the Republican nomination, but Mr Cameron has declined several opportunities to retract it since he became front-runner.
At a press conference at the conclusion of the G7 summit in Ise-Shima, Japan, Mr Cameron was asked whether he would like to congratulate Mr Trump, after US media reported he had secured the support of the 1,237 delegates needed to claim the nomination at the Republican convention in July.
Mr Cameron said: "On Donald Trump, I would congratulate anybody who can get through those marathon processes for leading one of the two great political parties in the United States of America. It is an extraordinary marathon. When I think of the campaign I held in 2005 - touring the UK to become leader of the Conservative Party - it was pretty exhausting, but it is a small campaign compared to the vast nature of what these candidates have been through. So anyone who gets through that gets my congratulations."
He added: "I'm not going to get involved at all in the American election - it's a matter for the American people to choose their next president.
"I believe in the special relationship. I believe the special relationship will work whoever is in whichever jobs in the UK or in the US - it's a shared interest about values and about security and prosperity in our world."
On the prospect of a Trump visit, Mr Cameron said: "Sometimes these candidates choose to come through various European countries in the run-up to US elections. I don't know whether this will happen this time. No dates are fixed.
"But I'm always happy to meet people on that basis and I've met other candidates before."