Under NATO rules, the secretary-general has to be decided “by consensus,” meaning that Rutte still has to garner the backing of all the remaining countries.

The official said that the discussions “are not final” but added: “There is increasing momentum behind his candidacy.”

Pressure is growing on NATO members to approve Rutte before the leaders’ summit in Washington in July. He would replace Jens Stoltenberg, who has helmed NATO since 2014.

U.S. Ambassador to NATO Julianne Smith said last week that allies should aim at “completing the selection process probably in the first quarter of this calendar year.”

Another senior NATO official confirmed the number of countries that still need to support Rutte, saying that around 10 were still holding back from a yes vote.

“We will continue to hear their questions and concerns,” the first official said. “And we encourage … the Dutch mission at NATO to answer those questions.”