The EU’s Council president Charles Michel’s surprise announcement to run in the European election in June has put the bloc’s 27 leaders under pressure to agree on a replacement for the Belgian politician.

If they fail to agree on a successor – traditionally a former prime minister – the rules state that the head of the country holding the rotating six-month European Council presidency is to lead future meetings.

For many EU countries, Hungary's Prime Minister Viktor Orban, who holds the current rotating presidency, is problematic.

Mr Orban regularly clashes with the European Commission and has single-handedly held up aid increases to Ukraine.

This has prompted politicians to criticise Mr Michel, who is expected to be elected as a member of the European Parliament (MEP) in Belgium and thus resign before his council term ends in November.

Some, like Dutch MEP Sophie in ‘t Veld, have said his early departure would undermine his credibility as an EU politician because he would be placing his ambitions above the bloc's interest, thus “leaving the ship in the middle of the storm”.

Such criticism was to be expected in light of the turbulent current geopolitical climate, said Denis Duez, political science professor at University of Louvain in Belgium.

"There's a risk that the European Council will be weakened at a moment where consensus must be found on extremely important issues including the war in Ukraine," Mr Duez told The National.

The year is set to be a crucial year for Europe due to the record number of elections that will take place around the globe. Europeans will vote from June 6 to June 9 in elections while the US could also re-elect Donald Trump in elections in November.

Some have expressed worry that a return of Mr Trump could undermine Ukraine’s battle against Russia, viewed in Brussels as an existential threat to European democracy.

In parallel, the popularity of far-right politicians, often critical of financial support for Ukraine, is on the rise in EU heavyweights including France.

The EU has also struggled to find common ground in the face of the brutal war in Gaza that has so far claimed about 23,000 Palestinian lives after a Hamas-led attack on Israel killed 1,200 Israelis.

In Belgium, commentators have been quick to point at Mr Michel's track record of placing his personal ambitions first.

"With his mandate ending and elections coming up both at national and European level, he clearly wanted to make sure that he still had a job in politics next year," said Mr Duez.

Mr Michel has pushed back against such criticism. An official said he would "continue to be fully dedicated to his responsibilities as European Council President" until he takes his seat in the European Parliament in July.

Even before his announcement to run in the election, made in a weekend interview with Belgian media, EU leaders had been scheduled to meet in June to discuss who would lead European institutions, including the council, after the election. Negotiations usually take months.

An official said: “President Michel is returning for a direct scrutiny by and dialogue with the citizens. It’s the most natural democratic exercise for European leaders."

But Mr Michel’s decision means they will have less time than expected to decide if they want to avoid a scenario in which Mr Orban steps in between July and November.

EU leaders also have the possibility of nominating a temporary leader, which is the most likely scenario according to Jacob Kirkegaard, a senior fellow at the German Marshal Fund think tank.

"The probability of the job defaulting into Orban's lap is essentially zero," Mr Kirkegaard told The National.

"EU leaders do not have to rush into a decision. All they need to do is appoint a temporary president, and there are plenty of people who can do this job."

Who, then, could become the next president? Here are some of the most likely candidates.

Mario Draghi

The former Italian prime minister and head of the European Central Bank, Mario Draghi, is a popular figure in Brussels.

In September, the President of the European Commission Ursula von der Leyen asked him to draw up a plan to spur the EU’s economic competitiveness.

Media reports claimed that France was lobbying for Mr Draghi to succeed Ms von der Leyen at the head of the commission, but Mr Draghi said last month that he was not interested.

To complicate matters further, Ms von der Leyen has remained ambiguous about whether she wants to stay at the head of the commission for a second term amid rumours that she may want to become Nato’s next secretary general.

The mandate of Nato's current leader Jens Stoltenberg is set to end later this year. But in her State of the Union speech in September, Ms von der Leyen seemed to imply that she may seek a second term at the head of the commission.

Antonio Costa

Last year, socialist Portuguese politician Antonio Costa was rumoured to be among the top candidates to succeed Mr Michel. He was first elected as prime minister in 2015.

However, Mr Costa resigned from the premiership in November after police raided government offices on suspicions of corruption over lithium mining concessions and found tens of thousands of euros in cash in the office of his chief of staff. He is set to remain in his post until snap elections in March.

Although Mr Costa has denied any wrongdoing, the corruption scandal renders his appointment as EU Council president unlikely.

Mark Rutte

Mark Rutte, the Netherlands’ longest-serving prime minister, ticks many of the boxes to become the EU’s next council president.

Nicknamed “Teflon Mark” because of his ability to survive political storms, the liberal politician is viewed among his European peers as a skilled negotiator despite tension with some European countries over his hesitations to back financial bailouts during the Covid-19 pandemic in 2020.

However, a row over asylum policy caused his government to collapse in July.

Mr Rutte remains as caretaker prime minister as cabinet formation talks drag on after a snap election in November.

This means that Mr Rutte will probably be free for an EU job in the coming months. He is also viewed as a top candidate to become Nato chief – thanks, in part, to his strong backing of Ukraine since Russia’s full-scale invasion in February 2022.

Yet the Netherlands has a poor track record when it comes to defence spending, which might work against his candidacy.

Sanna Marin

Elected Finland’s youngest prime minister in 2019 at age 34, Ms Marin oversaw her country’s accession to Nato last year but quit politics in April after her political party, the Social Democrats, lost a national election.

Ms Marin is viewed as a strong candidate to head the European council because current polls show that the socialists are expected to come second at the European parliament election, behind the conservative EPP group.

Should Ms von der Leyen, an EPP member, continue to head the European Commission, the top council job would probably go to a socialist as part of the usual horse-trading for top EU jobs after an election.

A female candidate is also expected to be given priority because no woman has held the job of president of the European Council since it became a full-time job in 2009.

"I think a current or recent female socialist prime minister would have a very good case," said Mr Kirkegaard.

However, it remains unclear if Ms Marin would be interested in a job in Brussels.

After she resigned, she joined the Tony Blair Institute as a strategic counsellor. In September, she signed with talent management firm Range Media Partners, signalling her interest in the entertainment industry.