BUCHAREST, May 19, 2025 (BSS/AFP) - Nicusor Dan, the centrist mayor of Bucharest, won a tense rerun of Romania's presidential election on Sunday, beating nationalist George Simion in a vote seen as crucial for the direction of the EU and NATO member bordering war-torn Ukraine.

The ballot came five months after Romania's constitutional court annulled an election over allegations of Russian interference and a massive social media promotion of the far-right frontrunner, who was not allowed to stand again.

Dan, who campaigned for an "honest" Romania, gained close to 54 percent of the vote, while US President Donald Trump admirer Simion secured some 46 percent, according to near complete results.

"It's the victory of thousands and thousands of people who... believe that Romania can change in the right direction," Dan, 55, told supporters, who chanted "Europe" and "Russia, Russia, Romania is not yours".

Turnout was close to 65 percent, compared to 53 percent for the May 4 first round, in which Simion secured most votes.

"The mobilisation was almost unprecedented," political scientist Sergiu Miscoiu told AFP, adding "never has an election been so decisive, with clear geopolitical implications."

Romania's president has significant sway in foreign policy, including holding veto power at EU summits.

- 'People's will' -

EU chief Ursula von der Leyen congratulated Dan, vowed it would help work towards "a strong Europe". French President Emmanuel Macron said Romanians had "chosen democracy, the rule of law, and the European Union... despite many attempts at manipulation".

Ukrainian President Volodymyr Zelensky also congratulated Dan, saying it "is important to have Romania as a reliable partner".

Despite exit polls showing Dan ahead, far-right leader Simion, 38 said he had won the election, but eventually conceded defeat to his rival.

"I would like to congratulate my opponent, Nicusor Dan. He has won the election, and this was the will of the Romanian people," Simion said in a video on Facebook.

He vowed to "continue our fight" for Romania and to put its 19 million people "first".

Simion, who leads the far-right AUR party, has criticised what he called the EU's "absurd policies" and proposed cutting military aid to Ukraine.

Simion and Dan both campaigned on a platform of change amid anger over the politicians, deemed corrupt, who have ruled one of the EU's poorest countries since the end of communism 35 years ago.

Simion voted in Mogosoaia, just outside Bucharest, with far-right politician Calin Georgescu.

Georgescu was the front-runner in last year's cancelled presidential election and was barred from taking part in the rerun.

As the duo arrived, dozens of people, some holding flowers, shouted: "Calin Georgescu for president."

- Tense atmosphere -

The election campaign took place in a tense atmosphere.

The cancellation of last year's vote and subsequent barring of Georgescu drew tens of thousands onto the streets to protest in sometimes violent rallies.

Top US officials also criticised the decision to scrap the last ballot.

The surprise resignation of Prime Minister Marcel Ciolacu and the collapse of his pro-European government coalition -- after their candidate failed to make the runoff vote -- further raised the stakes.

The new president will have the power to appoint a new prime minister.

The election turmoil has increased economic uncertainty in the EU's most indebted country, which has grappled with high inflation.

"The stakes of these elections are huge because there is widespread chaos in Romania right now after the annulment," voter Runa Petringenaru told AFP.

"We can't wait for it to be over," the 55-year-old workshop organiser added.