Ben Wallace has said he plans to resign at the next Cabinet reshuffle after four years as Defence Secretary.
He told The Sunday Times he would stand down as an MP at the next election but ruled out leaving “prematurely” and triggering another by-election for the Conservatives to battle.
Mr Wallace, who survived three prime ministers in his current role, played a key role in the UK’s response to Russia’s invasion of Ukraine and was a close ally of Boris Johnson.
His Wyre and Preston North constituency will disappear at the next election after boundary changes and he said he would not seek a new seat.
“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,” he told the paper.
He suggested he will continue to call for higher defence spending, which he has campaigned for throughout his time in the role.
Mr Wallace had expressed an interest in standing for the position of Nato secretary-general before it was announced the current chief, Jens Stoltenberg, had been given another year in charge.
The minister told The Economist there were a “lot of unresolved issues” in the military alliance and “it’s not going to happen,” and 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 has 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.”
The Prime Minister distanced himself from the comments, saying the Ukrainian president has “expressed his gratitude for what we’ve done on a number of occasions”.
Mr Wallace is believed to have told Rishi Sunak on June 16 of his plans to stand down from Cabinet.
He told the Sunday Times his departure was due to the strain the job had put his family life under.
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.
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.
Mr Wallace ruled himself out of the running for the Conservative leadership last year, despite being an early frontrunner in the race to replace Mr Johnson.
