Iohannis's withdrawal would clear the way for the Dutch prime minister to succeed Jens Stoltenberg as head of the defence alliance later this year.

"About NATO, more tomorrow. I will present these issues first to the CSAT (Supreme Council of National Defence), then to the public," Iohannis said at a news conference Wednesday alongside Italian President Sergio Mattarella, who was visiting Bucharest.

"Tomorrow afternoon you will be fully informed and we will move forward," he said.

Iohannis, 65, has vowed to bring a "renewal of perspective" to the alliance as a member of its eastern flank.

"It is time" for Romania, which joined NATO in 2004, to "assume an even greater responsibility within the Euro-Atlantic leadership", Iohannis said when announcing his bid in March.

Leading NATO powers spearheaded by the United States are pressing to get an agreement on a new head of the alliance before a summit meeting in Washington next month.

Romania, which borders Ukraine and the Black Sea, has gained increased strategic importance since the start of Russia's invasion of Ukraine in February 2022.

The country hosts more than 5,000 foreign troops, the largest contingent anywhere in NATO's southeastern region.

The nomination of a new NATO secretary general requires consensus from all 32 alliance members, and most appear ready to back Rutte -- though Hungary had remained opposed until this week.

On Tuesday, Hungary's nationalist Prime Minister Viktor Orban said he was "ready to support" Rutte's candidacy after securing a guarantee from the Dutch leader that Budapest would not have to contribute to any coordinated NATO arms deliveries for Ukraine.

Rutte currently serves in a caretaker capacity as prime minister and is set to leave his position in the coming weeks once a new Dutch government is installed.