US President Joe Biden expressed his support for the candidacy of outgoing Dutch Prime Minister Mark Rutte as the next secretary-general of the North Atlantic Treaty Organization (NATO) ahead of its 75th anniversary summit in Washington in July.

A US official revealed to Politico on the condition of anonymity that Biden's support for Rutte's bid to the Western defense bloc would likely sway more allies to get on board after months of discussion on who should succeed Jens Stoltenberg upon the expiry of his term this October.

Biden has yet to reveal his decision on the matter publicly.

Earlier, it was reported that two-thirds of NATO countries backed Rutte's nomination.

Stoltenberg has been serving as NATO boss since 2014 and has steadily navigated the bloc through a complex decade in transatlantic politics.

Under NATO rules, the secretary-general has to be decided by unanimous consent, meaning that - just like decisions on whether to admit countries into the alliance - all 31 member nations would have to agree on who should become NATO boss.

This also meant that Rutte had to get through Turkey and Hungary, who have since made a dogged defiance in admitting Sweden into the bloc.

Read Also: Dutch Government Collapse: PM Mark Rutte to Leave Politics After November's General Elections

(Photo: Marcelo del Pozo/Getty Images)

Race for NATO's Top Job

Rutte is not the only one expressing interest in becoming the next NATO secretary-general, as Estonian Prime Minister Kaja Kallas and Latvian Foreign Minister Krišjānis Kariņš. However, both Baltic politicians have yet to declare their candidacies.

If Rutte becomes NATO boss, he would be put on a collision course with Russia, which the alliance has been seeking to oppose since its invasion of Ukraine. He would also have to deal with Republican Party skepticism and Donald Trump if he ever returns to the White House after an election in November.

Despite this, the Dutch premier did not discuss his NATO bid during the Munich Security Conference, saying he had learned his lesson in October when he suggested that he was interested in the job.

It was previously reported that Rutte had been criticized for his government's poor defense spending, prompting Trump also to make a threat not to support NATO countries not doing enough to spend on its defense industries, a remark Stoltenberg has since criticized.

"I made the mistake in October talking about, 'I might be interested in that role' and then that mushrooms," he told reporters in Munich last week. "I shouldn't have done that, so I decided not to talk about that anymore."

Meanwhile, Dutch Chief of Defense Staff Gen. Onno Eichelsheim said Rutte would "very likely" get the top job.

Related Article: New NATO Chief Front-Runner Dutch Prime Minister Mark Rutte Faces Criticism Over Poor Defense Spending