A young leader marches to office promising sweeping change and buoyed by hopes that he will introduce a new style of politics to replace a rejected establishment. He seems to walk on water and to be in touch with his times as he injects fresh life into international gatherings and invites pop stars to the official residence. Tony Blair 1997 or Emmanuel Macron 2017; Cool Britannia at Downing Street or, as we saw last week, Rihanna and Bono at the Élysée Palace to discuss world education and poverty.

But if it took half a dozen years for the Blair halo to lose its lustre, the French president is already facing negative comments that he is a bit too good to be true, that he is proving too big for his boots and that his promised new start for France will run aground on the familiar problems that stymied his predecessors. Undeterred, however, by the criticism and falling poll numbers, Macron forged ahead last week with initiatives ranging from nationalising the country’s biggest shipbuilder, STX France, to presiding at a meeting where Libya’s two main rival leaders agreed to call a ceasefire and hold elections, as his wife Brigitte bounded down the steps of the palace to greet Rihanna.

Three months after his election became inevitable as he faced the rightwing Front National’s Marine Le Pen in the second round of the presidential battle, the inevitable is continuing to happen. The youngest of French presidents is becoming embroiled – whether he likes it or not – in the everyday business of government. He says he wants to rule as a “Jupiter” operating above the political maelstrom as he delivers thunderbolt judgments and instructions. His model is Charles de Gaulle, who established the semi-monarchical presidency of the Fifth Republic in 1958 to enable him to rule above party divisions in a way that would bring the French together behind his leadership.

It didn’t work out quite like that for the general, who was forced into an unwelcome run-off ballot at the 1965 presidential election and resigned four years later after losing a referendum vote. In France, partisan political divisions and pressure from vested interests never go away. The question is whether the president can gain enough support to transcend them, as De Gaulle did in the early years of the Fifth Republic, or whether they dictate events, as has happened under Macron’s three predecessors.

Tuesday: Macron brokers a meeting between warring factions in Libya. Photograph: Jacques Demarthon/AFP/Getty Images

As spring turned to summer, the former investment banker, whose previous government experience consisted of two years as economy minister under François Hollande after serving as an adviser, was riding high. The luck he had enjoyed since launching his presidential campaign a year earlier, and the skill he showed at making the most of it, held as opponents bickered and his movement seemed the obvious answer to the hole in the middle of French politics.

His 65% score in the presidential run-off was followed by a sweeping victory for his new party République En Marche! (REM) at legislative elections where it won an overall majority in the National Assembly. The mainstream opposition parties, the Socialists and the centre-right Républicains were humbled and divided. There was growling from the hard right and left of Marine Le Pen’s Front National and of Jean-Luc Mélenchon’s La France Insoumise (France Unbowed) and four ministers were forced to step down over allegations of misuse of funds or political funding chicanery. But the president’s approval rating in the polls rose from 62 to 64% in June as he set out his Jupiterian stall in a didactic manner reminiscent of De Gaulle on subjects ranging from African civilisation to France’s responsibility for the round-up of Jews in Paris in 1942.

Not content with domestic matters, he sought to raise his country’s global profile with a series of meetings with foreign leaders designed to ram home the message that “France is back” after the lacklustre Hollande presidency. The economy perked up in line with a general upswing in the eurozone.

France sounded a hard line on Brexit. Macron focused on building the relationship with Angela Merkel as an essential element in his ambitious plans for reform of the eurozone. He received Vladimir Putin at Versailles, reading him a lesson about Ukraine and Russian propaganda while hinting at a more flexible attitude on Syria. Despite laying out his differences with Donald Trump on globalisation and climate change, the 39-year-old president invited his 71-year-old American counterpart to the Bastille Day parade on the Champs-Élysées, where the visitor enjoyed the military show but seemed nonplussed when the Republican Guard broke into a synchronised routine while playing a medley of hits by the French electronic duo Daft Punk that had Macron and the assembled dignitaries clapping their hands.

Then reality started to cast a shadow over the king of the gods. His government began to implement practical steps to achieve aims he had laid out during his election campaign. Reducing the budget deficit to the EU target of 3% and making the economy more competitive means measures that may sound good on paper but are unwelcome when put into practice. Such as cutting the military budget by €850m – something that caused a huge public row and the resignation of the head of the armed forces this month. Such as cutting housing subsidies and social security allowances – which sparked widespread protests, heightened when the government unveiled proposals for partial lifting of the wealth tax. Such as the plan to relax the labour laws to reduce job protection – prompting unions to mobilise for street protests in the autumn.

Macron and his ministers have their reasons. Liberalising the elephantine labour code to make it easier to fire staff in a downturn should diminish the reluctance of employers to take on new workers in an upturn. Lifting the wealth tax on investment should encourage rich people to sink money into start-ups. But the impact, coupled with denunciations from the opposition of presidential “authoritarianism” in dealing with the armed forces chief, the 60-year-old Pierre de Villiers, helped to pull Macron’s opinion poll rating last week down 10 points to 54%, lower than either of his two predecessors, Hollande or Nicolas Sarkozy at the same stage of their presidencies.

Wednesday: Brigitte Macron greets Rihanna at the palace. Photograph: Imago / Barcroft Images

The ending of the honeymoon was inevitable, and Rihanna and Bono – or the Republican Guard bopping on the Champs-Élysées – are not going to do much about it. If he is to keep his credibility, not just at home but also with the all-important partner in Berlin, Macron has to stick to his guns. He may be encouraged by the rise in economic growth and a fall in the long-running scourge of unemployment. By nationalising the country’s biggest shipyard last week to prevent an unwelcome Italian takeover and by talking of the EU applying European preference in public procurement programmes, the president is showing that as well as being a defender of free trade and globalisation, he also perpetuates the old Colbertist streak of looking after France first, which always plays well.

But gods always have problems dealing with mere mortals, as De Gaulle found in the end. The sour mood that gained ground in France over the past two decades should make it easier for Macron to implement the kind of changes he promised, to modernise outdated structures and free up the all-powerful state. But that requires a leap of faith from citizens who have been let down by successive heads of state since the mid-1990s.

Macron has to fight against that heritage. Doing so may require some low-down politics as well as didactic exhortations as he faces the threat of a “social coup d’état” from Mélenchon. The question is whether the president represents a real desire for change from the essentially conservative course in which vested interests of left and right have repeatedly blocked progress and politicians have not been ready to risk unpopularity since Jacques Chirac retreated from the reform programme on which he was elected in 1995.

Or will Jupiter, too, quail? If he does, not only will conservative France have won again, but Europe will be weakened. If he does not, his popularity will fall further, whoever he invites to the palace. As the country settles into its long summer break, the test facing the occupant of the Élysée looks like the most important issue for Europe.

Jonathan Fenby is author of The History of Modern France: From the Revolution to the War on Terror, and The General: Charles de Gaulle