Forty-eight hours before Romanians were due to vote in a presidential election run-off, the whole process was scrapped because of an unprecedented ruling by the constitutional court.

The court’s decision to annul the first round came after a far-right independent candidate, Calin Georgescu, came out of almost nowhere to lead the first round two weeks ago amid allegations of Russian interference.

Georgescu has condemned the ruling as a coup and Romania may have to wait months to vote again.

Why this decision matters

Romania is a key Nato member on its eastern flank and shares a long border with Ukraine.

It is not the first Eastern European state to fend off Russia’s hybrid war, and the constitutional court has ruled that intelligence revelations of Russian meddling are sufficiently serious to put the presidential vote on hold.

Moldova’s recent presidential vote was held amid alleged Russian interference and voter fraud, and across the Black Sea in Georgia, the pro-Western opposition says contested elections there were hit by Kremlin meddling.

Why has the vote been annulled?

Opinion polls were almost neck and neck going into Sunday’s race. Almost 19 million Romanians were eligible to choose between Calin Georgescu and liberal mayor and former TV journalist Elena Lasconi.

Latest polls even gave Lasconi the edge in the run-off.

But then on Wednesday Romania’s outgoing President Klaus Iohannis declassified intelligence documents from the supreme council for national defence suggesting that almost 800 Tiktok accounts created by a “foreign state” in 2016 were suddenly activated last month to full capacity, backing Georgescu.

Another 25,000 TikTok accounts had become active only two weeks before the first round.

Romanian foreign intelligence said Russia was the “enemy state” involved and had engaged in hybrid attacks including tens of thousands of cyber attacks and other sabotage.

Domestic intelligence put Georgescu’s sudden surge in popularity down to a “highly organised” and “guerilla” social media campaign” that involved identical messaging and social media influencers.

TikToks promoting him were not marked as election content, violating Romania’s laws, it said, while one account paid out $381,000 (£300,000) in the space of a month to users who pushed Georgescu’s candidacy, while he said he had not paid anything for his campaign.

That decision to declassify intelligence documents changed everything.

Judges from the constitutional court met on Friday to consider a large number of requests to annul the first round.

It was a complete about-turn from a decision four days before that approved the initial 24 November vote after a complete recount of 9.4 million votes.

What does the ruling say?

In its single-page judgement, the constitutional court says that in order to ensure the fairness and legality of the electoral process it has unanimously decided to annul the entire vote and the government must establish a new date for a re-run.

The court says cites its role under the constitution “to guard the observance of the procedure” of presidential elections.

It stresses the decision is final and binding.

The president in Romania wields considerable power as commander-in-chief of the armed forces and with the task of appointing the prime minister.

Who is Calin Georgescu?

Calin Georgescu, who calls himself a university teacher, was a relative unknown in the presidential race.

He denies he is a fan of Vladimir Putin, although he sees the Russian leader as a “patriot and a leader” and wants to put an end to political and military aid to Ukraine.

“Zero. Everything stops,” he told the BBC’s Sarah Rainsford. “I have to take care just about my people. We have a lot of problems ourselves,” in words that reflect his Romania-first stance.

He says while Romania should remain in international organisations such as the EU and Nato, it must end its “subservient” role.

He also condemns allegations that Russia was behind his electoral success as intelligence “lies”.

A 62-year-old agricultural engineer by profession, he held high-ranking civil service jobs years ago at Romania’s environment and foreign ministries.

He is also a conspiracy theorist who believes Man never landed on the Moon and the Covid-19 pandemic never happened, despite the seven million deaths worldwide, reported by the World Health Organization.