The political future of Brazil’s former president Jair Bolsonaro has been cast into doubt after electoral judges banned him from running for office for eight years for abusing his powers and peddling “immoral” and “appalling lies” during last year’s acrimonious election.

Five of the superior electoral court’s seven judges voted to banish the far-right radical, who relentlessly vilified the South American country’s democratic institutions during his unsuccessful battle to win a second term in power. Two voted against the decision.

The verdict means Bolsonaro, who lost last year’s election to his leftist rival Luiz Inácio Lula da Silva, will only be able to seek elected office again in 2030, when he will be 75.

The move to bar Bolsonaro from seeking public office was based on his highly controversial decision to summon foreign ambassadors to his official residence last July, 11 weeks before the election’s 2 October first round.

At the meeting, Bolsonaro made baseless claims against Brazil’s electronic voting system which caused a public outcry and were denounced by one supreme court judge as politically motivated disinformation.

Bolsonaro’s lawyer argued that while his client’s tone at the meeting with the envoys might have been inappropriate and “excessively blunt”, he had merely been seeking to “improve” Brazil’s voting system.

However, casting his vote against Bolsonaro, Judge Floriano de Azevedo Marques claimed Bolsonaro had tried to obtain an unfair advantage in the election with his “abnormal” and “immoral” actions. In belittling Brazil’s democracy in front of the foreign audience, the judge accused Bolsonaro of making their country appear like “a little banana republic”.

The court’s president, Alexandre de Moraes, said the decision to ban Bolsonaro reflected the court’s faith in democracy and its “repulsion towards the shameful populism which has been reborn from the flames of hateful and anti-democratic speech and statements which propagate disgraceful disinformation”.

Judge Benedito Gonçalves, who also voted against Bolsonaro, slammed the ex-president’s “deceitful monologue” and “appalling lies”, arguing they had been designed to “arouse a state of collective paranoia” among voters.

After Friday’s ruling, Bolsonaro compared the court’s decision to the attempt to assassinate him on the eve of the 2018 election, which he won. “[Then] I was stabbed in the belly. Today I was stabbed in the back,” he told reporters.

In the run-up to last year’s profoundly divisive election, the Donald Trump-admiring populist repeatedly attacked Brazil’s electronic voting machines, insinuating he might reject the result if he deemed the vote unfair.

Millions of followers embraced the idea of such a conspiracy and on 8 January 2023, one week after Lula’s inauguration, thousands of diehard Bolsonaro supporters stormed and ransacked the presidential palace, congress and the supreme court hoping to overturn the election.

“The idea was to get rid of Lula,” one participant told the Guardian the morning after the attacks in the capital Brasília.

Subsequent federal police investigations into the 8 January uprising – which Lula’s government called a botched coup – have revealed that figures close to Bolsonaro discussed possible ways to engineer a military intervention that would remove Lula from power in the weeks after their leader’s defeat.

One document, reportedly found on the mobile phone of Bolsonaro’s aide-de-camp Mauro Cid, Lt Col Mauro Cid Barbosa, contained a detailed blueprint for reversing Lula’s victory. According to that plan, the outgoing president would send a report outlining his grievances to military chiefs who would then appoint a special “administrator” tasked with “re-establishing the constitutional order”.

Supreme court judges deemed hostile would be deposed and their election-related decisions annulled, before a fresh election was called at an unclear future date. The news magazine Veja, which first reported the plot, called it “The Road Map for the Coup”.

The sidelining of Bolsonaro, the dominant figure on the Brazilian right, has sparked speculation over who might inherit the formidable 58m votes he received last year.

On the eve of Friday’s vote, Veja claimed Bolsonaro’s ostracism “could mark the end of the career of one of the most controversial characters in the history of the republic and the start of a new and completely unpredictable phase in Brazilian politics”.

Some suspect Bolsonaro’s wife, the evangelical former first lady Michelle Bolsonaro, may emerge as a presidential candidate in the 2026 race, although she has also faced federal police scrutiny over suspected financial irregularities. She has denied wrongdoing.

Others believe a more likely heir is Bolsonaro’s former infrastructure minister, Tarcísio de Freitas, who last year became governor of São Paulo and is less radical than his mentor. Romeu Zema, the multmillionaire governor of Brazil’s second most populous state, Minas Gerais, is also considered a possibility, as is the governor of Rio Grande do Sul, Eduardo Leite, and Bolsonaro’s former agriculture minister, Tereza Cristina. Some suspect Bolsonaro might seek to anoint one of his politician sons, the senator Flávio Bolsonaro or the congressman Eduardo Bolsonaro, who has cultivated ties to Trump.

Friday’s vote may only be the first in a series of blows to Jair Bolsonaro’s political fortunes. He also faces criminal investigations into claims he deliberately incited the 8 January riots, was involved in faking coronavirus vaccination certificates, and sought to take possession of expensive jewellery gifted by the government of Saudi Arabia.

Bolsonaro has denied misconduct, with allies painting efforts to force him from politics as a witch-hunt likely to boost his popularity. “My goodness gracious, this is an injustice,” Bolsonaro told reporters as he flew to Rio’s city airport on Thursday, where one passerby was filmed berating him as a “coup-mongering crook”.