Mark Rutte, the departing prime minister of the Netherlands who has guided more than $3 billion in Dutch military support to Ukraine since 2022, on Thursday clinched the last assurance he needed to become NATO’s next secretary general.
On Thursday, President Klaus Iohannis of Romania dropped his bid to lead NATO, making it all but certain that Mr. Rutte, 57, would be formally elected to a four-year term at the helm of the Atlantic alliance.
That could take place as soon as next week, ahead of a high-level NATO summit in Washington in July. The Netherlands is a founding member, and Mr. Rutte would be the fourth Dutch official to become the organization’s top diplomat.
Even if that happens, he would not immediately assume responsibility for the 32-nation alliance. Mr. Rutte, who has been the leader of the Netherlands since 2010, remains prime minister in the country’s transitional government, and a diplomat who requested anonymity in line with protocol, said the current NATO secretary general, Jens Stoltenberg, was for now expected to stay until his term ends in October.
Mr. Rutte has increasingly echoed a main NATO message that supporting Ukraine in its defensive war against Russia is vital for preserving democracy and national sovereignty across the alliance.
“This war is not simply about defending the freedom of the Ukrainian people; it is also about protecting the freedom and security of the Netherlands,” Mr. Rutte is quoted as saying at the top of his government’s website. “So we will not abandon those most in need.”
Still, Mr. Rutte is not seen as unwilling to deal with Russia or with Moscow’s few allies in NATO, as had been the case with some candidates from Eastern Europe or the Baltic States who also had expressed interest in the top job.
“It is a consensus organization, so you have 32 allies that you need to bring on board,” said Camille Grand, a former NATO assistant secretary general who is now at the European Council on Foreign Relations. “If you’re perceived as leaning toward one particular geography of the alliance, or too dovish or too hawkish, then it makes things complicated.”
“There was a concern that it was important to have someone who is perceived as in the middle ground of the alliance, rather than on the edges of the debate,” Mr. Grand said. “So he was ticking all the boxes.”
Mr. Grand knew and worked with Mr. Rutte when they overlapped at NATO headquarters in Brussels. “He was always pretty mainstream in the room,” Mr. Grand said. “He was never the guy who was difficult on anything, but always very supportive of NATO, sometimes even to the point of criticizing his peers when they were not loyal enough.”
Mr. Rutte’s criticism of Hungary in 2021 was seen as almost costing him the top NATO job.
Hungary is both a member of NATO and of the European Union, and its leader, Prime Minister Viktor Orban, has exasperated officials in both organizations for imposing some authoritarian policies and maintaining relations with President Vladimir V. Putin of Russia. In 2021, Mr. Orban’s government restricted L.G.B.T content in the media and schools, eliciting “deep concern” from E.U. leaders and prompting Mr. Rutte to declare that Hungary “has no business being in the European Union anymore.”
That set off three years of acrimony between the two men, and led to suggestions by Mr. Orban that he would not support Mr. Rutte’s candidacy as the NATO chief, whose election requires unanimous consent within the alliance. But Mr. Orban backed down last week as part of an agreement that Hungary would not provide or otherwise support NATO efforts to continue sending military aid to Ukraine for the duration of the war.
In a letter to Mr. Orban on Tuesday, Mr. Rutte said he would respect that agreement “in a possible future capacity as NATO secretary general.”
But Mr. Rutte stopped just short of apologizing for his remarks about Hungary.
“I also took note that some remarks I made in 2021 as prime minister of the Netherlands have caused dissatisfaction in Hungary,” Mr. Rutte wrote in the letter, dated June 18. “My priority in a possible future capacity as NATO secretary general will be to maintain unity and treat allies with the same level of understanding and respect.”
NATO allies who backed Mr. Rutte’s bid have sought to lock down support ahead of the July meeting in Washington. Mr. Iohannis, the Romanian president, dropped out of the running after Mr. Orban’s concession made it clear that Mr. Rutte’s bid had widespread support. On Thursday, Mr. Iohannis endorsed Mr. Rutte and announced that Romania would send one of its urgently needed Patriot air defense systems to Ukraine.
Mr. Rutte announced last July that he would not seek re-election in the Netherlands after his government was split over the issue of Dutch asylum for migrants and refugees.
In October, he told Dutch radio that he found the job of NATO’s civilian chief “very interesting,” and by February, he had secured the backing of the United States and of European powers.
Mr. Rutte is not married, lives in the same house in The Hague that he bought as a student with friends, and often rides his bike to work.
He is a fan of classical music and of U2, and his favorite film is the 1979 movie “Hair,” according to a 2015 profile in the English-language Dutch News.