A narrow majority of 50.39% voted “yes” in Moldova's key referendum on joining the European Union, preliminary results showed, after President Maia Sandu said Sunday's double votes were marred by “unprecedented” outside interference be.

The razor-sharp result – less than 1% of the ballot papers still have to be counted – is anything but a clear confirmation of the pro-EU course that Sandu pursued for four years at the head of the small former Soviet republic between Russia and the West.Sandu received in a simultaneous presidential election, she won 42% of the vote, while her main rival, former Attorney General Alexandr Stoianoglo, won 26%, a better result than polls had predicted.

The result sets the stage for a closely contested runoff between the two on November 3rd. Stoianoglo said that if elected, he would build a “balanced” foreign policy that includes relations with the EU, the United States, Russia and China.

Sunday's double votes, which came after persistent allegations of election interference, were seen as a test of the southeastern European country's aspirations to join the EU by 2030 and finally move away from Moscow's sphere of influence.

Moldova's future has been in the spotlight since Russia invaded its eastern neighbor Ukraine. Russia maintains a small contingent of troops stationed as peacekeepers in the Transnistria region, which has broken away from Moldova.

In the run-up to Sunday's referendum, polls showed a clear majority in favor of joining the EU. A “yes” result means that a clause defining EU accession as a goal will be added to the constitution.

In the early hours of Monday, Sandu told Moldovans there was “clear evidence” that criminal groups working with “foreign forces hostile to our national interests” had tried to buy 300,000 votes.

She said this represented a “fraud of unprecedented proportions” and that Moldova would “respond with firm decisions.”

“Criminal groups… have attacked our country with tens of millions of euros, lies and propaganda, using the most nefarious means to trap our citizens and our nation in insecurity and instability,” she said.

The Kremlin condemned Moldova's votes as “not free,” cast doubt on what it said was a “difficult to explain” surge in votes for Sandu and the EU, and called on the Moldovan leader to provide “evidence” of interference.

The EU jumped to Sandu's defense, saying Moldova had faced “truly unprecedented intimidation and foreign interference from Russia and its proxies” in the run-up to that vote.

The close result of the referendum could put Sandu in a weaker position ahead of the second round, given her support for EU integration.

Moldova began the long process of formal accession negotiations in June and is aiming to join by 2030 under Sandu. Relations with Moscow have soured as Sandu condemned the Kremlin's invasion of Ukraine and diversification of energy supplies away from Russia.

Stoianoglo boycotted Sunday's referendum, calling it a ploy to boost Sandu's electoral victory.

Ahead of the vote, authorities repeatedly issued statements alleging that Russia-based fugitive tycoon Ilan Shor had made Russian-backed attempts to interfere in the vote.

Russia, which accuses Sandu's government of “Russophobia,” denies interference, while Shor denies wrongdoing.

Police have accused Shor, who was sentenced in absentia to prison for fraud and involvement in the theft of $1 billion, of trying to pay a network of at least 130,000 voters to vote “no” and to support “our candidate” election.

Shor has openly offered on social media to pay Moldovans to persuade others to vote a certain way, saying it was a legitimate use of his money.

In the early hours of the morning he declared that Moldovans had voted against the referendum and told Sandu: “Today I congratulate you, you have lost the battle.”

Political scientist Valeriu Pasha said that the “yes” vote, which initially lagged behind in the vote count, only moved forward slightly due to the unusually high turnout among Moldovans living abroad, who overwhelmingly support EU integration.

“In elections like this, where tens of (percentage points) can be bought, it will be very difficult for us to continue. But we must learn lessons and learn to combat this phenomenon,” he wrote on Facebook.