In how many different ways can François Fillon, the beleaguered Republican candidate to the French Presidency, shoot himself in the foot?  Yesterday, he was placed under formal investigation over alleged “diversion of public funds and misappropriation of money” and a few of his hard-core supporters, who still believe he was targeted to prevent the traditional Right from winning the Élysée, are starting to falter.

The crisis has lasted 40 days and 40 nights, and it all started with #Penelopegate. On 25 January, the satirical political weekly Le Canard Enchaîné revealed that Fillon’s discreet, Welsh-born wife Penelope, had received, as his “parliamentary assistant”, over half a million euros from the Parliamentary budget  for some 15 years.

Employing your relatives has, until now, been legal for French MPs; paying them for no work at all isn’t. It soon proved impossible to find anyone at the Assemblée Nationale building in Paris who’d seen Mrs Fillon there. She wasn’t registered and had no security badge.

In time-honoured French political tradition, Fillon stonewalled, denying everything. His wife, he said, helped him in his constituency. In equally time-honoured, muckraking tradition damning details just kept on emerging.

It wasn’t half a million, but a million euros, over two decades. It wasn’t only Fillon’s wife, but two of his children. It wasn’t only the National Assembly but a respected monthly journal, La Revue des Deux Mondes (est. 1829) once Balzac, Dumas and Baudelaire’s publishers. They’d paid Penelope Fillon large sums of money for precious little work: 100,000 euros over 15 months, in which she seemed to have written two short book reviews (400 words in total).

The flow of money didn’t only come from state funds, but from one of the country’s wealthiest men, Marc Ladreit de Lacharrière (722nd in Forbes’s Richest List). A one-time L’Oréal CEO, he is now the main shareholder in the financial services holding company Fimalac, which owns, among a number of investment funds, one of the “big three” worldwide ratings agency, Fitch. (Perhaps coincidentally, Fitch was the last to downgrade French debt during the 2008 financial crisis, long after its American competitors Moody’s and Standard & Poor.)

In a move that, 150 years ago, would have been chronicled by Balzac himself, Lacharrière had bought La Revue in 1991 from an industrialist and former Résistance hero, Jean Jaudel. Within a few years, he turned it into one of the French establishment’s major networking power bases.

There’s a Revue des Deux Mondes annual literary prize; there are dinners of the great and not so good; you haven’t arrived in French politics if you haven’t been invited to guest-speak at one of those. Fillon, of course, has. He has also featured on the magazine’s cover several times.

Lacharrière has a grand house in the Sarthe, not far from Le Mans, in Fillon’s constituency. So has Henri de La Croix de Castries, the former chairman of AXA, the world’s largest insurers. De Castries, the nephew of one of France’s most famous generals, and a descendant of Louis XV’s Minister of the Navy, is also a Fillon supporter. He is credited with writing large parts of Fillon’s manifesto, and is widely tipped to become his Finance, or his Defence minister, in case Fillon beats all odds and is elected President on 7 May.

As journalists examined the list of Fillon’s declared interests, they noted that AXA as well as Lacharrière had paid fees to Fillon’s personal consultancy, set up only a few days before MPs were no longer allowed such arrangements while holding office.

Fillon, who easily won the Conservative primary back in December on his “Mr Clean” reputation, bitterly attacked the speed with which judges had hauled him up – with great publicity – for interrogation within 24 hours of the first Canard Enchaîné piece. He was also outraged that the transcripts of these sub-judice interrogations were being regularly leaked to Le Monde and Médiapart, a left-wing website.

At campaign rallies, Fillon started lumping the press with the judiciary, à la Trump, in his all-purpose swipes. His audiences lapped it up, but to investigative journalists here, this was the equivalent of the Glorious Twelfth.

And then, last Sunday, Le Journal du Dimanche brought us #suitgate. Since 2012, they revealed, Fillon had received 48,500 euros’ worth of bespoke suits and luxury clothes at Paris’s most prestigious tailors, Arnys, from an anonymous donor.

Some 30,000 euros had been paid, in cash, for three of Arnys’s signature corduroy Forestière country jackets – once a wardrobe favourite of the late François Mitterrand, at 5,000 euros a pop – as well as a selection of cashmere jumpers at 2,000 euros and 7,000-euro suits. The last purchase, three weeks ago, of two suits, was paid with a hand-delivered 13,000-euro cheque, drawn on the controversial Italian Banca Monte Paschi.

Fillon’s defence was if anything more tone-deaf than it had been following Penelopegate. “A friend made me a present of some clothes. I don’t see how this is anything but private,” he told Les Echos, the business daily, conveniently forgetting that sitting MPs are supposed to declare any gift above 150 euros to the Assemblée transparency register.

But no investigation was necessary for #hookednosegate, an own goal by Fillon’s social media team over the week-end. After a surge of support for Emmanuel Macron, the avowedly independent former Economy Minister, Team Fillon tweeted a cartoon linking Macron to all the notorious left-wingers who’d just declared for him, including a former Secretary General of the French Communist Party.

Unfortunately, the cartoonist’s idea of a former Rothschild’s investment banker – which Macron was for a couple of years before becoming Hollande’s deputy Chief of Staff at the Élysée – included a silk top hat, a hooked nose, and a red sickle suggestively cutting off the end of a fat cigar. Twitter ran riot for a couple of hours, comparing the (soon deleted) tweet with unsavoury Pétain-era anti-Semitic caricatures, at which point Fillon apologised fulsomely enough.

And then, yesterday, Le Parisien broke #weddinggate. Fillon’s law-student daughter, Marie, and his junior lawyer son, Charles, who have been interrogated by the investigative magistrates on the family’s case, received some 80,000 euros altogether over the years from Parliamentary funds for unspecified “legal research” performed for their father.

Investigators were surprise to see both had paid about two thirds of this into their father’s bank account. Marie Fillon volunteered that she was repaying her parents for the cost of her recent wedding: “Which is only natural since they didn’t pay for my brothers’ wedding reception expenses.”

At this point, people’s patience was running out. Many of his supporters thought they had picked someone close to their ideal: an old-fashioned provincial with a strong Catholic faith and an un-blingy lifestyle – the anti-Sarkozy.

But as revelation after revelation unfolded, Fillon’s relationship to money and sartorial finery started looking more like a Belle Époque Grande Horizontale’s than the austere Charles de Gaulle’s, whose name he had taken in vain during the primary to deride both Sarkozy and Juppé.

A week has never been a longer time in French politics. On March 5, haemorrhaging supporters (a counting app for defectors set up by the left-wing daily Libération briefly reached 306 names), with poll numbers slipping him in to third place behind Marine Le Pen and Emmanuel Macron, Fillon foiled an attempt by Nicolas Sarkozy and former Chirac PM Alain Juppé to oust him as a fatal liability to the party.

He splurged a sizeable amount of his campaign kitty on bussing conservative voters from the provinces for a well-attended rally in Paris. In front of the Eiffel Tower, the ever-silent Penelope at his side, Fillon called himself a “Résistant” threatened by dark forces, and vowed never to give up on his presidential bid.

To his beleaguered band of followers, such tenacity was admirable. They may not have numbered 200,000 on Place du Trocadéro, as the organisers optimistically announced, but they did pack the square and adjacent avenues solid, waving thousands of tricolours (handed out by the armful at security checkpoints) in the rain.

Otherwise very different from Trump voters (provincial, Catholic, affluent, every shade of middle class, feeling that nobody has represented their brand of unimaginative decency for decades), Fillon’s people are seized by the same righteous indignation at misrepresentations of them by the metropolitan elites.

The following day, Juppé and Sarkozy, whose single point of agreement had until then been the need to jettison Fillon, threw in the towel. Sarkozy instead negotiated key jobs in the campaign (and hypothetical Cabinet posts) for his closest associates.

But Juppé, who had noticed such Sarkozystes as the former Economy minister François Baroin, on the rain-swept Place du Trocadéro dais next to Fillon, felt Sarko had betrayed him. He threw a tantrum and resigned “definitely” from politics with extreme prejudice, calling the situation a “tragic waste” and all but vowing a pox on everyone’s house.

He went on to declare formal support for Fillon 48 hours later.

Since then, the situation has strangely solidified. A core group of Fillonistas, bloodied but unbowed, are ready to vote for their man no matter what. Some of them, shocked by #suitgate and the image it projects of Fillon’s elastic relationship to money, harbour few illusions about their man.

But they clench their teeth. They don’t like the alternatives; French politics has taught them that competent leaders, from Mitterrand to former Paris Mayor Jean Tibéri, can be economical with the honnêteté; and they are enraged at the accusations hurled as much at them as at their candidate.

In this they increasingly compare with Marine Le Pen voters, digging their heels in deeper at every insult or “revelation”. In a strange way, they were comforted by Fillon’s bone-headed stubbornness in the past 40 days: they feel he will show the same strength of will to ram through his reforms if elected.

This core numbers about 20 per cent in polls, while Macron and Le Pen supporters are neck to neck (26 per cent and 27 per cent). Marine’s voters are the most solid bloc, with 80 per cent declaring to pollsters they will not change their mind before polling day.

But over 60 per cent of Fillon supporters now similarly swear that their minds are made up. This compares favourably with Macron’s 38 per cent of unflinching supporters, and it has Macron’s people very worried. As one said: “Emmanuel can remain Teflon-coated only so long.”