编者按：2017年5月7日，埃马纽埃尔·马克龙赢得法国总统选举。《经济学人》杂志对这位法国历史上最年轻的总统表现出了明显的好感。

On May 14th, as Emmanuel Macron takes up his duties in the Elysée Palace, spare a thought for what he has already achieved. To become head of state he created a new political movement and bested five former prime ministers and presidents. His victory saved France and Europe from the catastrophe of Marine Le Pen and her far-right National Front. At a time when democracies are being dragged to the extremes by doubt and pessimism, he has argued from the centre that his country must be open to change, because change brings progress.

But spare a thought also for the difficult road ahead. Mr. Macron trounced Ms. Le Pen, but if you count abstentions, blank ballots and votes cast chiefly to keep her out, only a fifth of the electorate positively embraced his brand of new politics. Each of the past three French presidents has promised reform—and then crumpled in the face of popular resistance. Left-wing demonstrations against the new president in Paris this week hint at the struggle to come.

Much is at stake. The challenge from Ms. Le Pen did not begin with this election and it will not end with her defeat. If Mr. Macron now presides over five more years of slow growth and high unemployment, it will strengthen the far right and the hard left, which together got almost half the first-round vote. To put France beyond their reach, he needs to carry through vigorous economic reform. And for that, he needs first to impose his vision on French politics.

The next few weeks will be crucial. As president, Mr. Macron can force through a certain amount of change by decree. But to secure thoroughgoing, lasting and legitimate reform he needs the backing of the legislature. Hence in the elections for the National Assembly in a little over a month’s time his party, renamed this week as La République en Marche! (LRM), or “The Republic on the Move!”, needs to win a big block of seats.

That is a tall order. The party is just over a year old. Its local knowledge and tactical nous are untested. There is only a slim chance of LRM winning an overall majority.

Even if he controls the assembly, Mr. Macron will face France’s most potent source of resistance—street protests and strikes. That is what happened in 1995, when Jacques Chirac, at the beginning of his first term as president, waged a battle to reform the economy. After he failed, Mr. Chirac abandoned reform for his remaining decade in office. France is still living with the consequences.

If Mr. Macron too has only one chance at reform, his focus should be on the joblessness that has robbed the French of hope and which feeds Ms. Le Pen’s arguments that citizens are being failed by a greedy, ineffectual elite. The unemployment rate is close to 10%; for those under 25, it has been above 20% since 2009. Firms are reluctant to hire new employees because firing them is time-consuming and expensive. The 35-hour week, a thick wedge of taxes on employment and union dominated sectoral bargaining all put firms off creating jobs.

However, although the economics is straightforward, the politics is toxic. Each reform, much as it benefits a jobseeker, makes someone already in workless secure.

Mr. Macron therefore needs to be ambitious and swift. Ambitious because you can be sure that the left and the unions will fight even small reforms as hard as large ones: if Mr. Macron is to rally ordinary citizens against organised labour, he needs to make the fight worthwhile. And swift because, if reform is to succeed, now is as good a time as he will ever get. He is flush with victory. His party will start with the benefit of novelty. He can offer stimulus through apprenticeships and tax cuts. Most of all, he will be acting at a point in the cycle when France’s economy is growing—faster, indeed, than at any time since a brief post-crisis rebound in 2010. Labour-market reform takes years to bear fruit. Growth will buy him time.