BRUSSELS: Romania's president has withdrawn from the race to become NATO's next secretary general, leaving outgoing Dutch Prime Minister Mark Rutte all but certain to head the world's biggest military organisation from October.

The office of President Klaus Iohannis said in a statement that Romania's security council has backed Rutte's bid. It also said that Iohannis had informed NATO late last week that he intended to pull out.

His withdrawal removes the last real hurdle Rutte might face. It should allow NATO to put on a show of unity and demonstrate solidarity with war-ravaged Ukraine when US President Joe Biden and his counterparts meet in Washington on July 9-11 to mark NATO's 75th birthday.

NATO secretaries-general are responsible for chairing meetings and guiding sometimes delicate consultations among the 32 member countries to ensure that an organisation that operates on consensus can continue to function.