Macron's victory could be short-lived

He said that structural reforms to improve the country's economic and social situation, as well as issues like security, identity, the place of religion in society, or migration would be the main challenges for the new leader of the EU’s second biggest country.

Macron, a centrist pro-EU candidate, is the favourite, with around 60 percent of voting intentions, according to the last polls published ahead of the vote.

But his ambitions could be quickly crippled by lack of a clear majority in parliament after another round of elections in June, De Marcilly said.

If the far-right candidate Le Pen was elected against the odds, she would be confronted by other EU countries' opposition to her plans to create a double currency system in the EU and transform the bloc into a looser alliance of nation states.

Noting that 10 out of the 11 candidates in the first round of the election's first round had opposed the Maastricht treaty in 1992 or the EU constitution in 2005, De Marcilly said that "Brussels was relieved to see that with Macron, there was still a candidate with a real European inspiration".

He added however that Macron would have to "not just talk, but convince" France's EU partners that he could use Europe's improving economic situation to push through the structural reforms they were waiting for.

Macron's challenge

France already had three extensions of the deadline to comply with EU deficit targets and it would be "complicated to arrive and ask for a fourth extension”, he said.

"Macron can have a political momentum but it will be short," De Marcilly warned, adding that this could come as a surprise for France's partners.

"Few in Brussels understand the difficulty to govern with a very fragmented parliament, and that [French political] culture is not a culture of coalitions but of show of force“ he said.

Macron, who entered politics only a year ago, leads En Marche! (Marching Forward), a political movement that is not yet organised as a real party.

Even if the two main traditional parties, the centre-right Republicans and the Socialist Party were eliminated in the first round of the presidential vote, they could still win many seats in the National Assembly.

This makes a pro-Macron majority "very hypothetical", De Marcilly said.

"Macron's challenge will be to propose something that sufficiently unites and mobilises voters to accompany the momentum until the legislative vote”, he said.

While the results of the first round showed that parties and their voters had sometimes "radically different world views", it will be “difficult for Macron to reconcile them in less than a month," the political scientist said.

The campaign showed that French people had "fears over France's place in the EU and in the world," he said.

Sunday's run-off has also become a kind of EU referendum because the two last standing candidates are those who hold the most opposite views.

European approach

A year after Brexit, Macron has defended the case for EU membership and global influence, pointed out De Marcilly.

For Macron, "the EU allows us to be more powerful. It is about sharing sovereignty to gain more sovereignty at a higher level, which is logical if you put things into perspective."

In accordance with that view, De Marcilly added, Macron is more didactic about the sharing of powers in the EU.

He takes the time to explain that powers can be at a local, national, but also European level.

He has made clear that the EU "is not about abandoning sovereignty but that it is something you have to share, and that it justifies a European approach" to policies.

By contrast, Le Pen's EU view is to "do without Europe as a vehicle for power or protection, and that France is strong enough to assert its interests", De Marcilly said.

Le Pen has said that she wanted to renegotiate EU treaties to create a "European alliance of free and sovereign nations" and organise a referendum on France's EU membership.

Her flagship proposal had been to lead France out of the euro, but a week before the second round she said this was no longer a "prerequisite" for her economic policies.

Le Pen "hit the wall of reality" as she came closer to "potentially being elected," De Marcilly observed. "Not everything is doable".

If she was elected, Le Pen's EU policies would be "confrontational," he said, while the EU has been established to foster dialogue.

"She wants to end Brussels' diktat, which is a funny thing to hear from an MEP," he noted, adding that this approach "is worrisome in Brussels and raises questions" about Le Pen's real objectives.

De Marcilly pointed out that Le Pen would probably find no allies in her attempt to redesign the EU, even among the most critical countries.

"There are other countries that want to go back on power sharing [between the EU and member states], especially with an illiberal model of economy and society," he said.

'France cannot fall'

"But they do not want to leave the EU, and all that comes with it, while Le Pen says that if she is not listened to, she will take France out of the EU. One cannot see who could join her on that position," he insisted.

If France were to leave the EU, "the other 26 members could stay together, but it would not be the same thing," De Marcilly said.

"The shock of Brexit was absorbed" because the UK was not in the eurozone, he said, while a so-called Frexit would "hit one of the fundamentals" of today's EU - the sharing of monetary powers - and "impact the EU's abilities as a global player".

With Macron or with Le Pen, the outcome of Sunday's vote and how the next French president will govern in the coming months will be crucial for the EU as much as for France, De Marcilly observed.

"France cannot fall from the ship, otherwise the ship will sink," he said.