Far-right populist Călin Georgescu, who came from nowhere to win the first round of last year’s presidential election, has been detained by police and is facing criminal proceedings on a series of charges.

Georgescu was stopped in traffic in the capital, Bucharest, on his way to register as a candidate for new elections in May, after last December’s second-round run-off was annulled by the constitutional court.

Prosecutors said one of the charges involved attempted “incitement to actions against the constitutional order”.

Two right-wing populist parties said they were mobilising their supporters to head for the prosecutor’s office, where Georgescu was taken for questioning.

Police were seen erecting barriers around the building and hundreds of demonstrators gathered to protest.

Prosecutors said Georgescu was also being investigated for giving “false information, false statements” and for setting up an organisation with “fascist, racist or xenophobic characteristics” as well as forming an antisemitic organisation.

The severity of the indictment could jeopardise Georgescu’s bid to run in the presidential election on 4 and 18 May.

He has been placed under judicial control and told not to leave Romania, according to reports. As he left the prosecutor’s office, Georgescu told supporters he would continue to fight and that there was “no difference between the communist mentality and system [that collapsed in 1989] and now”.

The original presidential vote was cancelled before the second round last December, after the then president, Klaus Iohannis declassified intelligence documents that suggested that hundreds of TikTok accounts had been activated backing Georgescu.

Romanian foreign intelligence said Russia had been behind the move, as well as thousands of cyber-attacks and other sabotage.

Iohannis had decided to stay in office until a successor was elected, but he resigned earlier this month ahead of an impeachment vote.

Opposition politicians had at the time accused Iohannis of an undemocratic move, and Georgescu’s communications team repeated the claim against prosecutors.

“Where is democracy now?” they posted on X on Wednesday, tagging President Donald Trump, Elon Musk and US Vice-President JD Vance.

Earlier this month, the US vice-president accused Romania of annulling the elections based on “flimsy suspicions” of Romanian intelligence and pressure from its neighbours.

Romanian Foreign Minister Emil Hurezeanu accused Elon Musk of a “form of interference” in Romania’s elections, after the billionaire posted several messages of support for Georgescu.

Georgescu’s hopes of running for the presidency may end up at the constitutional court, which barred another far-right, pro-Russian candidate from running last year.

The decision to turn down Diana Sosoaca’s candidacy because of her views was widely criticised in Romania.

Romania is a vital part of Nato’s eastern flank as well as being a member of the European Union.

Călin Georgescu has been accused of being pro-Russian and he has praised Romania’s fascist and nationalist leaders from the last century as heroes.

He denied he was “Moscow’s man”, in a BBC interview last year, but referred to Vladimir Putin as a “patriot and a leader” while pointing out “I am not a fan”.

Meanwhile, Romanian police said they had carried out raids in several counties around the country, targeting 27 individuals as part of a criminal case relating to the creation of an organisation “with a fascist, racist or xenophobic nature”.

Investigations were also being conducted into false statements regarding the sources of election campaign funding, police said.

The statement made no mention of Georgescu himself and it was not clear if the raids were linked, however he said he was fighting a security system “that wants us in slavery”.