There is no official procedure for electing NATO's leader and it is impossible to predict the outcome, said MEP and former defense and foreign affairs minister Sven Mikser (SDE) on Thursday.
Prime Minister Kaja Kallas (Reform) said this week she is open to being considered for the role of NATO's next secretary general after Norway's Jens Stoltenberg vacates the seat next year.
However, it is difficult to assess Kalllas' chances and impossible to predict the outcome of the process, Mikser told ERR.
There is no "clearly regulated" procedure for candidates but a consensus is needed for someone to be offered the top job, he said: "There aren't any official candidates as such, it's not like the selection of an Olympic city."
Stoltenberg's 12-month extension suggests it has been hard to find a consensus candidate.
"Obviously, there will be a certain amount of animosity between countries from time to time, and there are bound to be some candidates who, for one reason or another, are more difficult for some Member States to accept," the MEP said.
"The smaller the Member State, the less likely it is that a candidate endorsed by one or other of the major powers will be vetoed, there must be some very clear red lines. Obviously, for the big countries, saying no comes more easily."
But whatever happens, the process will not be widely publicized until a consensus has been reached. "But before then it is still largely pure speculation," he said.
There is an understanding that neither the USA nor a representative from the current secretary-general will be given the role. Successful candidates usually have experience as prime ministers, defense, or foreign affairs ministers.
Alongside Kallas, outgoing long-time Dutch Prime Minister Mark Rutte also put himself forward for the role. Asked to assess his chances, Mikser said his experience gives him "many strong points" but again emphasized the informal nature of the selection process.
Mikser said he did not want to comment on Kallas' strengths and weaknesses but said, in terms of her experience, she can be discussed as a serious contender. He said he did not want to speculate on her chances as there is no formal selection process.
However, one factor that may be taken into consideration is geography.
"Some regions of Europe, for example, feel that they have been kept out of the loop for too long. Certainly, that can be used as a kind of argument, not that it necessarily adds very much at the end of the day," the MEP said.
This could add weight to Kallas' appointment as there has never been a secretary-general from the alliances' eastern flank.
Another consideration is that NATO has never had a female leader and there have been calls to rectify this.
"There are certainly very strong prominent women in Central and Eastern Europe. It seems to us that there is not much of a shortlist apart from our candidates. But that is not necessarily the case," Mikser said.
"Candidates from Eastern Europe are certainly stressing that it is really time to stop this distinction between the old and the new and that Eastern Europe should certainly be given a prominent position of some kind."
But at the end of the day, these arguments may not carry much weight. "It certainly does not mean that the next secretary general cannot be a man and cannot come from Western Europe," he said.
Stoltenberg has served two-four four-year terms, starting in 2014. His mandate was extended for 12 months last July after Russia's full-scale invasion of Ukraine and he will step down as secretary general next summer. Negotiations for his successor have been going on for some time, Mikser said.
"The search is certainly on, and the red lines and exclusions are certainly being probed and explored to see who might have the ambition and the will. So it's definitely happening somewhere," he told ERR.
"And I cannot rule out the possibility that someone somewhere in some capital city has already drawn a red line through one or other of the two names that have been put forward."
Other names rumored to be in the running for NATO's top job in recent years include former Estonian President Kersti Kaljulaid, Prime Minister of Denmark Mette Frederiksen, former Lithuanian Prime Minister Dalia Grybauskaite, and the UK's former Defense Secretary Ben Wallace.
Kallas has previously said she does not think she will get the job because she comes from a country on the eastern flank.
Editor: Mait Ots, Helen Wright