Mark Rutte, the outgoing Dutch prime minister, on Thursday 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.

But he had to use all the diplomatic skills gleaned during almost 14 years in charge of the Netherlands to win over hold-outs led by Turkey and Hungary.

Mr Rutte overcame Turkish reticence with an April visit to Istanbul, before finally sealing a deal with Hungary’s Viktor Orban at a European Union summit this week.

That left the last sticking point as Mr Iohannis, whose surprise bid had ruffled feathers among allies banking on a smooth appointment for Mr Rutte ahead of a Nato summit in Washington next month.

Romania’s security council on Thursday announced that Mr Iohannis had formally withdrawn and that the country backed Mr Rutte.