Story highlights UK Foreign Secretary Boris Johnson says "no vacancy" for post

Farage says endorsement was "bolt from the blue"

London (CNN) The UK has rejected a suggestion by US President-elect Donald Trump that it should appoint the figurehead of the Brexit movement, Nigel Farage, as ambassador to the US.

Trump caused diplomatic ripples when he said on Twitter that Farage, interim leader of the anti-immigrant UK Independence Party (UKIP), would "do a great job" in the post.

Many people would like to see @Nigel_Farage represent Great Britain as their Ambassador to the United States. He would do a great job! — Donald J. Trump (@realDonaldTrump) November 22, 2016

A spokesman for the office of British Prime Minister Theresa May blocked the idea, telling CNN the UK appoints its own ambassadors and that the position was filled.

Trump's expression of a preference for UK ambassador to Washington was a startling break with diplomatic protocol. It is unheard of in recent years for any US official to make such a suggestion to an ally.

It was particularly awkward for the UK as Farage has long been a thorn in the side of May's Conservative party. UKIP's political surge forced her predecessor, David Cameron, into holding a referendum on Britain's membership of the European Union. That ended in the shock vote to leave the EU and Cameron's political downfall.

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