Chancellor George Osborne avoided questions on his Conservative Party leadership ambitions, saying his current job was "all-consuming".
Mr Osborne is seen as one of the frontrunners to replace David Cameron, who has said he will not seek a third term as prime minister.
He did not deny being a contender during an interview with BBC political editor Laura Kuenssberg in Berlin.
But he said he was "very focused" on the UK's EU renegotiations.
This involves "delivering the best possible deal for Britain, the best possible economic plan for Britain, and getting all those decisions right", he added.
Asked "what's wrong with being ambitious", the chancellor said he was "ambitious for Britain", listing his current roles and adding: "That is a huge task. I'm extremely honoured that I've been asked to undertake it, but it's all-consuming."
Mr Osborne was one of three possible replacements tipped by Mr Cameron when he announced he would not seek a third term, along with Home Secretary Theresa May and London Mayor Boris Johnson.
He is in Berlin to set out the UK's economic demands ahead of a planned in/out referendum on membership of the European Union.
