Departing Dutch Prime Minister Mark Rutte is expected to become the next head of Nato after his only rival, Klaus Iohannis, stepped aside on Thursday.
The withdrawal of Romania's president from the race cleared the way for Mr Rutte to succeed Jens Stoltenberg as secretary-general of the transatlantic defence alliance when the Norwegian's term ends on October 1.
It is a pivotal time for Nato, with the war in Ukraine on its doorstep and European nations concerned about the possible return of critic Donald Trump to the White House. Mr Trump previously threatened to pull the US out of the alliance or not protect allies that do not contribute enough.
A decade after Nato set a target for allies to spend two per cent of their gross domestic product on defence, only 23 hit that bar this year.
Mr Rutte will face the challenge of sustaining allies' support for Ukraine's fight against Russia's invasion, while guarding against any escalation that could draw Nato directly into a war with Moscow.
He will have the key role of marshalling aid from Kyiv's weary backers and corralling European allies to spend more on defence to defend against any potential future attack from Russia.
Nato countries - spearheaded by the United States - have provided 99 per cent of the foreign military aid that has helped keep Kyiv's forces in the fight since 2022.
Mr Rutte, 57, had been the favourite for the job after all other Nato members had already backed him. He has been a staunch ally of Ukraine and an outspoken critic of Russian President Vladimir Putin.
Mr Rutte, who spent 13 years in charge of the Netherlands, currently serves in a caretaker capacity as prime minister after the collapse of his coalition and is set to leave his position in the coming weeks once a new Dutch government is installed.
As it announced Mr Iohannis's decision, Romania's supreme defence council said it would donate one of the country's two operational Patriot systems to Ukraine, responding to pleas from Kyiv to its allies for more air defence assistance.
The alliance's governing North Atlantic Council could formally select Mr Rutte for the post in the coming days. Leading Nato powers spearheaded by the United States have been pressing to get an agreement on the new head before a summit meeting in Washington next month.
At the summit, Nato is set to take over a greater role in coordinating arms deliveries to Ukraine and wants countries to make a long-term pledge.
Kyiv at the same time is also pushing for membership.
The nomination of a Nato secretary general requires consensus from all 32 alliance members. Heavyweights the US, Britain, France and Germany threw their weight behind his bid early on, but it took longer to persuade Turkey and Hungary.
Turkey came on board in April, while Hungary had remained opposed until this week.
That changed on Tuesday when Hungary's nationalist Prime Minister Viktor Orban said he was "ready to support" Mr Rutte's candidacy after securing a guarantee from the Dutch leader that Budapest would not have to contribute to any co-ordinated Nato arms deliveries for Ukraine.
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. Mr Iohannis, 65, had vowed to bring a "renewal of perspective" to the alliance as a member of its eastern flank.
Mr Iohannis, whose second term as Romanian president ends this year, has repeatedly said eastern European states need better representation in Euro-Atlantic leadership roles.
Mr Stoltenberg led the alliance through its most consequential decades since the end of the Cold War.
He oversaw Nato's shift from an alliance mainly engaged in crisis management missions in far-off places such as Afghanistan back to its roots of defence against Russia.
Four countries have joined Nato since Mr Stoltenberg took office - Montenegro, North Macedonia, Finland and Sweden.
By giving the top job to Mr Rutte, the alliance will pass up the opportunity to appoint a first female secretary-general - something multiple member states had said they were keen to do.
Estonian Prime Minister Kaja Kallas was widely considered a contender for the role, with strong support from eastern European countries. But she was seen as too hawkish towards Russia by some western member states.
Who is Mark Rutte?
Mr Rutte's tenure as Dutch PM was marked by the shooting down of Malaysia Airlines flight MH17 over Ukraine in 2014, with 196 Dutch among the 298 killed.
Mr Rutte has many nicknames including "Teflon Mark" due to his resilience to scandals, and "The Trump Whisperer" for his ability to manage Donald Trump.
The first quality made him his country's longest-serving leader, bouncing back after resigning in 2021 when thousands of parents - many from ethnic minority backgrounds - were falsely accused of childcare subsidy fraud. He eventually stepped down last year after a bitter row over asylum sparked elections that resulted in victory for far-right leader Geert Wilders.
He is widely credited with rescuing a 2018 Nato summit by talking Trump around on defence spending, and he showed typical Dutch directness by brazenly contradicting the president in the Oval Office.
As well as cycling to his office or to meet foreign leaders, he is known to do his own shopping at the local supermarket and drives himself to meet the king in his humble Saab estate car.
Another viral video showed Mr Rutte spilling a cup of coffee at a government building and insisting on mopping it up himself, as cleaning staff applauded and he chuckled at his own clumsiness.
The youngest of seven children, Mr Rutte's father Izaak was a trader, while his mother Mieke was the sister of Izaak's first wife, who died in a Japanese internment camp in the Second World War.
He initially wanted to be a concert pianist, but after attending the prestigious Leiden University, he joined Anglo-Dutch consumer giant Unilever, including a stint at its peanut butter division, Calve.
He describes himself as a "man of habit and tradition" who has spent his whole life in The Hague and volunteers as a teacher.
