Ben Wallace has said he will step down as Defence Secretary during the next Cabinet reshuffle.
The MP - who has been in the Cabinet role for more than four years, serving under three prime ministers - then plans to step back from politics entirely by not to standing in the next general election, he has told the Sunday Times.
But Mr Wallace ruled out leaving “prematurely”, and triggering another by-election for the Conservatives to battle.
“I’m not standing next time,” he told the Sunday Times.
“I went into politics in the Scottish parliament in 1999. That’s 24 years. I’ve spent well over seven years with three phones by my bed.”
Mr Wallace remains supportive of Rishi Sunak and the Government and his departure is not understood to be related to the Conservative Party’s current challenges.
He told the prime minister of his plans to step down on June 16.
It is believed the next Cabinet reshuffle could take place in September.
Regarding what the future might hold for him once he has stepped back from politics, Mr Wallace told the Sunday Times: “I’m quite happy to go and work at a bar.
“I feel quite fulfilled, and that gives me lots of options. I sometimes think I’d just like to go and do things I love, like Formula One or horse racing — just do something completely different.”
Mr Wallace has played a key role in the UK’s response to Russia’s invasion of Ukraine and was a close ally of Boris Johnson.
Mr Wallace had expressed an interest in standing for the role of Nato secretary-general before it was announced the current chief, Jens Stoltenberg, had been given another year in charge.
He told The Economist there were a “lot of unresolved issues” in the military alliance and “it’s not going to happen”. He later downplayed the prospect of a future bid to run the organisation.
Last week, the Prime Minister shut down comments from Mr Wallace in which he suggested Ukraine should show “gratitude” for the military support it had been given.
Mr Wallace had made the remark after the country’s President Volodymyr Zelensky branded it “absurd” for Nato to insist there were still conditions for his nation to meet before it can gain membership once the war with Russia is over.
Mr Zelensky later said: “I believe that we were always grateful to United Kingdom.
“I don’t know what he meant and how else we should be grateful.”
Popular within the Tory party, Mr Wallace is the longest continuously serving minister in Government, having been security minister under Theresa May before being promoted to Defence Secretary by Mr Johnson and continuing the role under his two successors.
He was previously appointed as a whip in 2014 and a junior minister in the Northern Ireland Office in 2015 while David Cameron was prime minister.
The Wyre and Preston North MP ruled himself out of the running for the Conservative leadership last year, despite being an early frontrunner in the race to replace Mr Johnson.
