British defense minister Ben Wallace will not stand as a member of parliament (MP) in the next UK national election, and will leave government when Prime Minister Rishi Sunak carries out his next cabinet reshuffle, he told The Sunday Times newspaper.

Wallace, a member of the ruling Conservative party, has been MP for Wyre and Preston North and its predecessor constituency in northwest England since 2005.

He has been defense secretary for four years, helping lead Britain’s response to Russia’s invasion of Ukraine.

“I’m not standing next time,” he said in an interview with the newspaper, but ruled out going “prematurely” and forcing another by-election.

Sunak is facing three by-elections next week, and opinion polls suggest his Conservative party could lose all of them.

A general election must be held in Britain within the next 18 months. The Sunday Times said a cabinet reshuffle was expected in September.

The newspaper said Wallace told Sunak his plans on June 16 but had hoped to make the announcement over the summer before leaks forced his hand.

There had been speculation over Wallace’s future in recent weeks. Boundary changes will see his parliamentary constituency scrapped at the next election and he had not publicly sought another seat.

He had been considered as a potential successor to NATO Secretary General Jens Stoltenberg but Stoltenberg’s contract was extended this month by another year.

In the interview, Wallace said his greatest concern was the danger of military conflict with Russia, accidental or otherwise.

“If Putin loses in Ukraine, he will be deeply wounded,” Wallace said. “He’s still got an air force and he’s still got a navy — and we see his navy do quite aggressive manoeuvres. Putin is not done with us yet. There is an ability for him, in the next three or four years, to lash out.”

Wallace also warned Britain could be drawn into more conflicts.

“Towards the end of the decade, the world is going to be much more unsafe, more insecure. 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,” he said.