Ben Wallace is thought to be rowing with home secretary Suella Braverman as he prepares to quit frontline politics, announcing that he will resign his post as defence secretary at the next cabinet reshuffle.
The senior Tory also revealed that he will not seek re-election as an MP at the next election, but ruled out leaving “prematurely” and triggering another by-election for the Tories.
“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 Sunday Times on his desire to leave Westminster.
Mr Wallace is not going quietly, however, having become involved in a turf war with Ms Braverman about British soldiers being asked to cover for any gaps in Border Force staff this summer.
The defence secretary has refused Ms Braverman’s request for 750 troops to fill in for immigration officials who strike or are absent, according to The Mail on Sunday, claiming that the Home Office should have made contingency plans.
A source told the newspaper: “The home secretary must not be allowed to always rely on our hard-working armed forces to be there to mop up for Home Office incompetence. If she was so worried, she should have planned ahead.”
Ms Braverman is said to have demanded that 750 armed forces personnel be made available to cover immigration posts in the event of wider strikes at airports and sea ports, warning of major travel disruption.
But Mr Wallace reportedly only wants to spare 250 troops, in order to avoid cancelling leave. A Home Office source told the Mail that Mr Wallace “has halved the number of troops he’s willing to offer to help backfill jobs compared with the last round of strikes at Christmas”.
They added: “Now an impending summer of chaos seems to be of little concern – but it is for the millions of people trying to use our airports. It’s all so petty.”
Mr Wallace said his departure was partly due to the strain the job had put on his family life.
The senior Tory, who has separated from his wife, said: “While I am proud to have worked with so many amazing people and helped contribute to protecting this great country, the cost of putting that ahead of my family is something I am very sad about.”
He insisted that his exit was nothing to do with last week’s row over his comments on Ukraine, when he said that the West was “not Amazon” and that countries supplying weapons wanted to see more “gratitude”.
Rishi Sunak said in response to those remarks that the Ukrainian president had “expressed his gratitude for what we’ve done on a number of occasions”.
The defence secretary tweeted on Saturday that his comments had been “somewhat misrepresented”, saying he had meant that Ukraine “needs to realise that in many countries and in some parliaments there is not such strong support as in Great Britain”.
Asked if things were so “bad” for the Tories that even leadership contenders were quitting, trade secretary Kemi Badenoch said Mr Wallace should be “celebrated” rather than “worrying” about his exit.
She told Sky News’s Sophy Ridge on Sunday: “I’m sad that he is stepping down, but I understand that public service is something that is very gruelling and draining. I think we should be celebrating Ben’s public service rather than trying to link it to unrelated issues.”
Former cabinet minister Andrea Leadsom also tried to play down the significance of Mr Wallace’s departure, saying it was “completely reasonable” that he should want to step back. Ms Leadsom told the BBC that many MPs were getting tired of the “harassment on social media” and “vitriol in the press”.
Mr Wallace had expressed an interest in standing for the position of Nato secretary general before it was announced that the current chief, Jens Stoltenberg, had been given another year in charge.
The popular cabinet minister – who will leave his role during a reshuffle expected in September, having told Mr Sunak last month of his intention to leave – suggested that he will continue to call for higher defence spending.
Speaking to The Sunday Times, Mr Wallace went on to talk of his fears about future wars: “Towards the end of the decade … I think we will find ourselves in a conflict. Whether it is a cold or a warm conflict, I think we’ll be in a difficult position.”
Citing the China situation and “a total breakdown of politics in the Pacific”, he added: “You could find yourself by 2030 in a position of cold war.”
Frequently topping the Tory members’ poll of most popular cabinet ministers, Mr Wallace is the longest continuously serving minister in government, having been security minister before being promoted to defence secretary by Mr Johnson.
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.
The Wallace-Braverman row comes amid fears of more Border Force strikes. The PCS union, which represents immigration staff, demanded that the government match the pay rises of between 5 and 7 per cent offered this week to public-sector workers.
A government spokesperson said: “The Ministry of Defence have accepted a Military Aid to the Civil Authorities request from the Home Office, to provide support to Border Force in the event of staff industrial action.”