On a late February night in Brussels, François Hollande was bleary-eyed after two days without sleep, but also jubilant. He’d spent 16 hours overnight in Minsk, Belarus, with Angela Merkel, extracting a Ukraine ceasefire from Vladimir Putin. From there he’d gone straight to a summit of EU leaders. Aides advised rest but the French president was determined to chat about the other triumph of the day: the sale of 24 Dassault Rafale jets to Egypt, the first export deal for the French fighter after 20 years of vain effort.

“India has confirmed the order – er, I mean Egypt,” Hollande said. “I could have said Qatar, given the confusion of being so tired.” With a characteristic giggle he stumbled on. “We’ve worked out payment that is within the means of Greece . . . er, Egypt. I think I’d better stop or we won’t know who’s bought what.”

Long-winded and self-mocking, the performance was pure Hollande. A back-room politician for most of his career, he has always enjoyed schmoozing with journalists. In Brussels he often rambles on after other leaders have left and the staff start turning out the lights. But on that February night, there was a touch of something else. Hollande was exuding a new self-assurance and was obviously enjoying himself. His first two and a half years of fumbled administration had felt like a succession of disasters, from rising unemployment to character assassination by Valérie Trierweiler, the betrayed former first lady. But in January, events had offered a reprieve.

After the Kouachi brothers committed their slaughter at the offices of Charlie Hebdo on the morning of 7 January, the most unpopular French leader in modern times had come into his own. Alerted by a friend’s text message from the scene, the unloved Socialist had ignored his security men and rushed from the Élysée Palace to the blood-spattered offices of the satirical magazine while the bodies were still on the floor. Rallying the nation in the days that followed, Hollande struck the right tone of solemnity and empathy. Leading the march of a million people through Paris on 11 January, he inspired a sense of communion around the republic’s values of liberty, equality and fraternity.

The plump little 60-year-old who had won election as “Monsieur Normal” no longer seemed such a lightweight. He had finally assumed the stature expected of France’s monarchical presidents. “François Hollande has suddenly come together,” the veteran commentator Alain Duhamel wrote in Libération. “For the first time, he embodied the nation and made us proud.” Le Figaro, Hollande’s chief media adversary, voiced its admiration. “He has become audible again when most of the French had given up on him,” it said.

At every opportunity since then Hollande has been invoking the “spirit of 11 January”. But the “Charlie effect” has faded and France has fallen back into la morosité that has coloured the national mood for two decades. Hollande’s Parti Socialiste (PS) has returned to feuding. His approval ratings have fallen again after the January spike. He lost 6 points from mid-January, dropping to 26 per cent on 20 February, against a record low of 16 per cent in November, according to Odoxa polling. Meanwhile Marine Le Pen’s Front National (FN) made a strong showing in the first round of national county council elections that end on 29 March. The FN secured 25 per cent of the vote, beaten into second place only by the centre-right alliance led by Nicolas Sarkozy’s Union pour un Mouvement Populaire (UMP).

Yet Hollande is sure that he has changed the way people look at him and is convinced he has transformed his presidency. Friends from his days at the École Nationale d’Administration (Éna), the finishing school of the governing elite, are unsurprised. “You wouldn’t think it, but François has always had an absolute belief in his destiny and it has remained unshaken despite the battering of the past two years,” a classmate from his 1980 year group at Éna told me after she visited him in December. This matches what Stéphane Le Foll, another member of the inner circle, told journalists in 2012 when he was helping manage Hollande’s campaign to defeat Nicolas Sarkozy. “People have always underestimated François,” said Le Foll, who is now the minister for agriculture and chief government spokesman. “There is a steel and clarity that you don’t see.”

***

To most people in France Hollande remains a mystery: insaisissable, ambiguous and blurred. People thought they had him pinned down when he won office as president with a muddled, old-style leftist manifesto, declaring war on “the world of finance” and harking back to the 1980s, the statist golden age of his mentor and hero, François Mitterrand. “We don’t have to go the way of the markets. I try to be coherent. We can do it the French way,” he told me in an interview on a train in late 2011, six months before his election, during the first Greek euro crisis. Then after piling on new taxes for 18 months, with the economy stagnant, and after failing to fulfil unwise deadlines for cutting the jobless rate, he made a U-turn. The micromanaging president followed up last spring with pro-business reforms, dumping left-wing ministers and appointing as prime minister Manuel Valls, a Blair-style moderniser. In a reshuffle soon after that, Emmanuel Macron, 37, an Éna-trained merchant banker who had served on Hollande’s staff, was promoted to run the economy ministry, where he has become the bête noire of the orthodox left.

Yet, despite multiple interviews, speeches and news conferences on the subject, Hollande has still not explained what he is up to with the economy. Unlike Valls, who gleefully breaches socialist taboo and embraces business, his language remains that of a leftist technocrat whose software was set in the 1970s. Much of France may have signed up to globalised competition – but not Hollande, at least not openly. It is not surprising that orthodox colleagues, such as Arnaud Montebourg, the maverick industry minister who was sacked last year, accuse him of betrayal. The sharpest attack on his leadership has come from Cécile Duflot, a former Green Party leader who was dumped from her job as housing minister a year ago. “His chief quality is his calm. His main fault is not saying what he thinks,” Duflot, 39, wrote in an account of her time in cabinet, From the Inside: Journey to the Land of Disillusion, published in August. Hollande had failed the left, she said. “By trying to be president for everyone, he has managed to be the president of no one.”

Aiming for revenge in the 2017 presidential election, Sarkozy went on the offensive in February, using the Europe 1 radio breakfast show to denounce Hollande as a serial deceiver. “When you lie to the French, there is a moment when you have to pay the bill,” Sarkozy said. “When you say you are going to run the country from the left . . . and then you do exactly the opposite, you create the conditions for revolt.”

It may not have damaged Hollande that France has learned that he is far from being a genial Monsieur Petites Blagues, or “Mr Little Jokes”, as he was once nicknamed by Laurent Fabius, a party rival who is now his foreign minister. Hollande always used the “straightforward nice guy” image as a cover in his decades backstage running the PS while Ségolène Royal, his former partner and the mother of his four children, stole the limelight as a minister and political star.

Valérie Trierweiler told me about Hollande’s secretive side when I interviewed her a few days after his election in May 2012. “He puts everything in compartments and doesn’t always show what he’s thinking,” she said. I put down Trierweiler’s obvious insecurity to her well-known obsession with Royal, who had eclipsed Hollande, the party leader, by running for the presidency in 2007 (she lost to Sarkozy). Royal and Hollande ended their three-decade relationship a month after her failed presidential campaign. At the time, he was already seeing Trierweiler, a reporter for Paris Match. Royal nevertheless publicly supported him when he ran for president in 2012, upsetting the possessive new companion.

It later emerged that Hollande’s visible coolness towards Trierweiler during the 2012 election campaign sprang not from Royal’s presence but from another source. He was secretly courting Julie Gayet, the actress whose liaison with the president was spectacularly exposed when Closer magazine published photographs of him visiting her overnight at a flat in Paris in January 2014. “I did not know that Julie Gayet was already hanging around – like a snake in the grass,” Trierweiler later wrote in Merci pour ce moment, her exercise in literary revenge that became France’s bestseller of the year. “I did not see her coming.”

France got a glimpse of Hollande’s cold side when he shrugged off the Gayet scandal and dismissed Trierweiler from his life with a one-sentence communiqué that he dictated to Agence France Presse news agency. In another blow to Trierweiler, Royal was ushered back into the palace three months later as minister for ecology and energy. She holds number-two rank in the cabinet, where she enjoys a complicity with the president that rankles with other ministers.

***

The publication of Trierweiler’s book on 5 September inflicted the only big emotional wound that Hollande has acknowledged suffering in office. As a man attached to modesty and discretion, he was stung by the scrutiny of his private life, both when his motor-scooter visits to Gayet exposed him to ridicule and when Trierweiler exacted her revenge. What really hurt, though, was Trierweiler’s portrait of him as a calculating cynic who loves luxury and mocks the poor, describing them as les sans-dents – the toothless people. (That was a play on the sans-culottes, the poor who wore trousers rather than fashionable breeches and who rose up during the 1789 revolution.)

On 8 September Hollande called in his biographer, the journalist Serge Raffy, and told him the story was “a lie that wounds me”. He added, “It hit me like a blow against my whole life. I have built my existence on the principle of helping others.” Although the son of a well-to-do Normandy doctor, Hollande had always felt humble because the family had been poor two generations earlier, the president said in his remarks, published by Raffy in the weekly Nouvel Observateur. “I have never cheated, never sought to make anyone believe I was someone other than who I am.” He was obliged to hide his emotions “because showing them would be deemed weakness on my part”, he said. “My character makes me keep steady, to be like tempered steel and at the same time humane.”

The claim never to have cheated might sound odd to Britons and other foreigners who have followed the palace soap opera, but this new, assertive Hollande has gone down well. The president has repeatedly turned to the theme of solid nerves, talking publicly of how the job has hardened him. It has not hurt that the man who seemed to have stumbled Forrest Gump-like into the Élysée after the disgrace of Dominique Strauss-Kahn, the early PS favourite, is now being depicted by opposition leaders as rather mean. “Hollande is very nasty; he has behaved like a bastard towards me,” said François Fillon, who served as prime minister under Sarkozy, speaking to Le Point in January. That outburst stemmed from a palace leak about Fillon’s alleged efforts to get Hollande’s team to raise the legal heat on Sarkozy, his rival, over past scandals.

The image of a tougher Hollande has reinforced his impressive performance on the foreign front as commander-in-chief and statesman. The most unmartial French president in decades has engaged troops for the past two years in a campaign against Islamist forces in Mali and elsewhere in the Sahel region. Last year, he sent French bombers and special forces in to Iraq to take on Islamic State and earlier he had been ready to bomb President Bashar al-Assad’s forces in Syria until events in London and Washington forced him to abandon imminent strikes.

In Europe, victory by the Syriza party in Greece and the rise of Matteo Renzi to prime minister in Italy have helped Hollande’s efforts to position France as a leading advocate for an alternative to German austerity.

After a frosty two years, Chancellor Merkel has started to treat Hollande as an equal, despite France’s continuing economic decline compared to Germany. Initially condescending, she now listens to him more in EU councils. Sarkozy, who prized his complicity with Merkel and privately derides Hollande as “pathetic” and a loser, was said to be envious when the chancellor invited Hollande to drive in the same Mercedes, with French and German pennants flying, to meet Putin in Minsk in February.

For all his satisfaction at winning respect at home and abroad, Hollande remains lucid over the outlook for his personal fortunes. Only the economy counts, as he knows. He dismayed his own circle by announcing in November that he would not stand for re-election if he has not managed to bring down unemployment. The jobless rate reached 10.3 per cent in December, falling back to 10.2 per cent the following month, against 9.7 per cent when he was elected.

Here, Hollande is hampered by his underlying failure: the refusal to clarify his course and ditch the left-wing rhetoric still beloved of the PS old guard and its clientele voters, dominated by civil servants, state-sector workers, teachers and the retired. They fault him from the left, demanding a return to protective socialism. Aurélie Filippetti, who was culture minister until she was dumped from the cabinet last summer, told RTL radio: “You can’t say in January, ‘France is under attack, France is at war,’ and then in February carry on the same policies that have led to a dead end, especially in employment.”

Filippetti is now one of the backbench mutineers making life tough for Hollande, Valls and Macron.

Being the product of his Éna, Mitterrandist background, Hollande still believes that France can prevail with its own model – a synthesis of enterprise and centralised administration by the state. That is the view of Dominique Reynié, an analyst who leads Fondapol, a centre-right think tank. “The conviction that you can change very little and the system will still hold is nearly unanimously shared in the governing elite,” he told me. Just as Mitterrand performed a pragmatic U-turn in 1983, imposing austerity to save the franc after two years of high-spending socialism, Hollande hired Macron and swung towards “social-liberalism” because he had no alternative. He has not undergone a conversion to the modern world, Reynié says. “The new direction in 2014 was useful and necessary but people don’t understand why he changed course. He hasn’t explained. Does it mean that what he said in the campaign wasn’t true? People on the left have lost their bearings.”

Like many in the commentariat, Reynié believes Hollande has finally grown into the presidency but he adds: “I don’t know how he will keep up this new trust from the people. What counts is unemployment and spending power and housing costs – things that affect people’s lives.”

The trouble is that, despite resentment against Hollande’s tax rises and general acceptance of the need for a competitive economy, much of France is still yearning for the reassuring state of old. Reflecting this, Sarkozy and his UMP have swung to a modernised form of Gaullist paternalism as they head towards the 2017 elections.

The biggest threat on the landscape is Marine Le Pen and the Front, who are busy stealing the old music of the PS along with its voters. The test in the local elections will be whether mainstream voters follow the old practice of crossing party lines in the run-off to block the far right, or whether the Front has gained enough respectability to win more than limited local power. A surge by the FN could set the stage for a presidential victory by Le Pen in 2017, a prospect that was inconceivable only a few years ago.

Dominique Reynié thinks France does not offer much of a model for left-wing parties elsewhere, such as Ed Miliband’s Labour, because the old statist creed has been rendered obsolete by globalised markets. “Time has run out for a European left that since the end of the 19th century has lived on the idea that you can mobilise the state and use taxes and public spending to organise social progress,” he says. That is certainly not the view of François Hollande and his nostalgic party. The young man who idolised François Mitterrand, the founder of modern French socialism, grew into a president who remains devoted to the creed of state-engineered social progress.

Charles Bremner is Europe editor of the Times