Nicusor Dan, the centrist mayor of Bucharest, won a tense rerun of Romania's presidential election on Sunday ahead of nationalist George Simion, near complete results indicated.
The vote was 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 more than 54 percent of the vote, while US President Donald Trump admirer Simion secured close to 46 percent, according to near complete results.
Turnout was close to 65 percent, compared to 53 percent for the May 4 first round, in which Simion was the leading candidate.
Both candidates claimed victory.
Dan, 55, told jubilant supporters gathered in a Bucharest park that Romania's "reconstruction" would begin on Monday, calling it "a moment of hope".
"In today's elections a community of Romanians who want a profound change in Romania won," Dan said.
Far-right leader Simion, 38, said "I am the new president of Romania," as he addressed cheering supporters in front of parliament.
He called on people at polling stations "not to allow any electoral fraud".
- 'Hallmarks of Russian interference' -
Romania's government said it had detected a "viral campaign of fake news" bearing the "hallmarks of Russian interference" after the founder of the Telegram platform, Pavel Durov, indicated that France had asked for Romanian conservative voices to be silenced.
France's foreign ministry said it "categorically" rejected Durov's allegations.
Simion and Dan both campaigned on a platform of change in the country of 19 million amid anger over politicians deemed corrupt who have ruled one of the EU's poorest countries since the end of communism 35 years ago.
"I voted thinking about a better life," Catalin Birca, 57, a pensioner in Bucharest, told AFP, adding that he wanted his country to remain pro-European.
"What are we doing otherwise? Going back to where we started from?" he added.
Dan has promised a country that is "honest".
Pledging to put "Romania first", Simion had vowed to "restore the dignity of the Romanian people.
He criticised what he called the EU's "absurd policies" and proposed cutting military aid to Ukraine.
The president has significant sway in foreign policy, including holding veto power at EU summits.
- 'Georgescu for president' -
Simion voted in Mogosoaia, just outside Bucharest, together with far-right 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."
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 last year's ballot.
The surprise resignation last week 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 and Simion's nationalist AUR party could enter government after negotiations on the formation of a new parliamentary majority.
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.
Discover the latest Business News, Sensex, and Nifty updates. Obtain Personal Finance insights, tax queries, and expert opinions on Moneycontrol or download the Moneycontrol App to stay updated!
