‘La République, c’est moi!’ Jean-Luc Mélenchon shouted, face-to-face with a police officer blocking the entrance to his office as it was being raided last month. ‘Kick down the door, comrades!’ he declared. The raids – on Mélenchon’s and his associates’ homes as well as the headquarters of his party, La France insoumise – were part of an investigation into the finances of his 2017 presidential campaign.

The sums involved are not especially extravagant: Mélenchon, whose campaign was the cheapest of the five main candidates’, is alleged to have overcharged on expenses by €35,000. But the discovery of €12,000 in cash at the apartment of a close ally is never a good look. Pierre Moro, who has been Mélenchon’s sidekick for decades, told police that he was entrusted with the money by the party treasurer.

At the heart of the controversy is the link between La France insoumise and Mediascop, a private communications company whose owner, Sophia Chikirou, is Mélenchon’s communications chief. Mediascop received a tenth of the Mélenchon campaign’s total spending, more than a million euros. As both service-provider and service-seeker, Chikirou could effectively set the price that the campaign would pay, and then claim it back from the state – a context in which charging €200 per minute for subtitling videos (it usually costs €15) and €250 to upload audio to Soundcloud starts to look a little suspicious.

Add in an inflated salary (Chikirou’s work was valued at €120,000 for eight months, on top of the money that went to Mediascop) and rumours of romance (Mediapart revealed that Mélenchon and Chikirou ‘have for some time been involved in an extra-professional relationship’) and you have all the ingredients of a good political scandal.

Mélenchon not only denies the allegations – he maintains he is the victim of a ‘Macronism-media-prosecutor’ conspiracy – but has repeatedly attacked journalists who dare to accuse him. He called reporters at France Info – who investigated Mediascop’s invoices and revealed the inflated fees – ‘liars’ and ‘idiots’, and told Mediapart that he expected better from them. The press, he says, is ‘the first enemy of free speech’, the police are ‘politicised’ and La France insoumise is the victim of a ‘witch hunt’.

His popularity has plummeted. His fourth-place finish in the first round of the presidential election belied a rousing campaign that saw him become both the leading figure of the French left (the ashes of the Socialist Party underfoot) and one of the country’s most popular politicians. Now, in the fallout of the ongoing investigation, he is one of its least popular, with the biggest drop among those who voted for him. According to a recent YouGov poll, 35 per cent of people have a negative opinion of him: only Marine Le Pen and Manuel Valls are more disliked.

‘We are not at war with the media, the justice system or the police,’ Mélenchon said recently. ‘But there is a section of the justice system, the police and the media that is at war against us.’ Political raids are relatively common in France – recent targets beside Mélenchon include the former prime ministers François Fillon and Dominique de Villepin, as well as the Front national (before it rebranded itself the Rassemblement national) – but Mélenchon’s team have tried to draw a connection between a pay rise for the head of France’s election auditing body, authorised by Macron, and the absence of any raid on the president.

Mélenchon’s combativeness with the press isn’t new. ‘In 2012, when we were polling 3 per cent, confrontations with reporters were our only way of existing,’ Chikirou told Le Monde in 2017. But the recent fights have a different feel to them. On 17 October, answering questions outside parliament, Mélenchon responded to one reporter by mocking her south-western accent, suggesting she wasn’t making sense, and asking her assembled colleagues: ‘Does anyone else have a question for me in French?’

Reporters Sans Frontières have reprimanded Mélenchon – not for the first time – and called his language ‘toxic and dangerous’ after he told his followers to ‘trash them’ (‘pourrissez-les’, referring to the France Info journalists) ‘wherever you can.’ When he called them ‘abrutis’ (‘idiots’), other reporters tweeted #jesuisunabruti in solidarity. ‘Demanding “the people” rise up against the media to chastise them and les pourrir doesn’t evoke the most glorious memories,’ the left-wing historian Roger Martelli observed. Nor does it draw the most positive comparisons with other leaders in the present.