Mark Rutte, the outgoing Dutch prime minister, has clinched the race to become the next head of Nato at a pivotal time for the alliance, after his sole challenger Klaus Iohannis, the Romanian president, pulled out.

The veteran politician, 57, is expected to be formally appointed by Nato’s 32 nations in the coming days and should take over from Jens Stoltenberg when the current secretary general’s term ends on Oct 1.

Mr Rutte will come in at a perilous moment for the Western allies as Russia’s war in Ukraine drags on and Donald Trump battles to reclaim the presidency in the United States.

After staking his claim for the job last year following the collapse of his coalition, Mr Rutte, a staunch Ukraine backer, quickly won the support of heavyweights Britain, France, Germany and the US.