Euronews examines the candidates and challenges for the position, while the appointment of Mark Rutte is not yet guaranteed.
NATO foreign ministers are meeting Thursday and Friday in Prague, Czech Republic.
They face the major decision of who should lead the transatlantic alliance in the years to come.
Norwegian Jens Stoltenberg, who took office in 2014, has already seen his mandate extended four times and is due to leave office on October 1.
The allies have almost converged on a choice, but obstacles remain.
Their decision comes at a key moment for the transatlantic military alliance, which must face the Russian threat and a potential second term for Donald Trump as American president.
How does NATO choose its Secretary General?
The Secretary General is NATO’s most senior official, selected by consensus by alliance members.
He is the one who chairs the main NATO committees, acts as spokesperson and recruits international staff.
In practice, the selection is done through informal diplomatic channels, but it is not easy to find a candidate who pleases all 32 allies.
According to a long tradition, now more or less formalized, the position is occupied by a senior European political figure and the usual duration of the mandate is four years.
Who are the candidates?
One candidate is the clear favorite: Mark Rutte, Dutch Prime Minister since 2010.
So far, his candidacy has received the support of 29 of the alliance’s 32 members, including the most influential, the United States.
Mr Rutte is expected to leave his post in the Netherlands soon. After months of post-election negotiations between the four coalition partners, former intelligence chief Dirk Schoof appears set to be named Dutch prime minister, meaning Rutte could step down as prime minister. here for a few weeks.
As leader of the liberal VVD party, Mr Rutte has managed a series of tricky coalitions in the highly fractured world of Dutch politics, although the VVD’s latest decision to ally itself with the extreme party PVV right of Geert Wilder, fuels the controversy.
But he is not the only candidate in the running. Romanian President Klaus Iohannis, who ran as a candidate last March, is still in the race, although he has far fewer supporters than Mr. Rutte.
Other potential candidates, including Estonian Prime Minister Kaja Kallas and then-British Defense Minister Ben Wallace, have withdrawn from the race and both now support Mr Rutte.
Northern Europe
Rutte’s appointment would be part of a trend of NATO leaders coming from northern European countries. The previous three being from Norway, Denmark and the Netherlands.
While this could spark protests elsewhere in Europe, Mr Rutte’s northern European pedigree could work in his favour.
Some fear that the appointment of a NATO leader who is too anti-Russian would further aggravate tensions, a factor which could have worked against Mr. Kallas.
Mr Rutte is pro-Ukraine. Ten years ago, it favored signing an association agreement between the EU and its eastern ally, although the PVV successfully campaigned against the agreement in a referendum in 2016, during of which 61% of Dutch voters rejected the ratification of the agreement.
What are the remaining obstacles?
If Mr. Rutte seems to be the favorite, there are still obstacles to overcome.
Hungarian nationalist Prime Minister Viktor Orbán has repeatedly vetoed EU aid to Ukraine and sanctions against Russia.
A few days ago, Hungarian Foreign Minister Péter Szijjártó confirmed that he would not support Mr Rutte, preferring Klaus Iohannis.
It is also unclear when and how Robert Fico might side with Mr. Rutte. The Slovak Prime Minister was seriously injured in a politically motivated attack in mid-May and is currently recovering in hospital.
What is happening now?
The Prague meeting could prove too non-political to break the deadlock. Hopes are focused more on the NATO summit which is to be held in Washington in July, following a meeting of defense ministers which will be held in mid-June.
But by postponing a decision until after the European elections on June 9, there is the risk of being caught up in a broader series of decisions concerning the direction of other Brussels institutions.
Mr Iohannis himself is sometimes tipped to lead the European Commission, although that post appears more likely to go to the incumbent, Germany’s Ursula von der Leyen.
Likewise, Mr Kallas could be Estonia’s choice for EU commissioner, or even end up heading the bloc’s diplomatic service.
Thus, the side agreements reached at the EU summits scheduled for June 17 and 27 could help unblock NATO’s dilemma.
All eyes will also be on the US elections scheduled for November, with some fearing that the result will be harmful to the transatlantic alliance.
Republican candidate Donald Trump has urged allies to meet agreed-upon military spending goals, and even called on Russia to attack those who fail to do so.