In a striking breach of diplomatic protocol, President-elect Donald Trump has suggested Nigel Farage, the “Brexit” champion who has been one of Trump’s most vocal foreign champions, should be made the United Kingdom’s ambassador to the United States.

The apparently unprompted tweet has set off a firestorm in the U.K., throwing another wrench in the gears of Prime Minister Theresa May’s attempts to rebuild the “special relationship” between Britain and the U.S. under Trump.

Downing Street put out a terse statement following Trump’s tweet, which was posted shortly before midnight local time, saying there was “no vacancy for an ambassador to the United States.” The incumbent, Kim Darroch, was appointed only in January and it would be a major departure for a government to appoint a sitting politician of a rival party to what is considered the crown jewel in the diplomatic service—especially at the prompting of a foreign world leader.

Trump said that Farage, a lawmaker in the European Parliament who is currently interim leader of the United Kingdom Independence Party, would do a “great job” as one of Britain’s most senior diplomats. “Many people” would like the appointment, Trump said:

Farage was a key figure in Britain’s June 23 vote to withdraw from the European Union, having long been a supporter of “Brexit” and a vociferous advocate during the referendum campaign. He was invited to appear alongside Trump at a Mississippi rally during the presidential campaign, inspiring voters to assemble for a Brexit-style surprise victory. After that victory became reality, Farage was photographed alongside the President-elect inside Trump Tower.

Their close friendship stands in contrast to Trump’s relationship with the country’s leader. Her 11th place ranking on the list of world leaders contacted by Trump after his Nov. 8 victory was perceived as a humiliation in the U.K., and was compounded when it emerged he had spent longer on the phone with journalist Piers Morgan following his victory.

May’s government confirmed earlier this week it was considering inviting Trump to the U.K. for a state visit in 2017, in an apparent attempt to rebuild a “special relationship” seen to have deteriorated under President Barack Obama. The timing of Trump’s tweet could suggest there might be strings attached to a rekindling of the affair.

Farage had previously said he was “not the ambassadorial type” but hinted in an article for Breitbart.com published just hours after the tweet that he would accept the role if asked. “I have known several of the Trump team for years and I am in a good position with the President-elect’s support to help,” he wrote. “The world has changed and it’s time that Downing Street did too.”

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