Emmanuel Macron was confronted on Monday with pressing reminders of the challenges facing him as France's next president, even as allies and some former rivals signalled their willingness to work closely with him.
The 39-year-old centrist's victory over far-right nationalist Marine Le Pen in Sunday's election came as a huge relief to European Union allies who had feared another populist upheaval to follow Britain's vote last year to leave the EU and Donald Trump's election as US president.
"He carries the hopes of millions of French people, and of many people in Germany and the whole of Europe," German Chancellor Angela Merkel told a news conference in Berlin.
"He ran a courageous pro-European campaign, stands for openness to the world and is committed decisively to a social market economy," the EU's most powerful leader added, congratulating Macron on his "spectacular" election success.
But even while pledging to help France tackle unemployment, Merkel rejected suggestions Germany should do more to support Europe's economy by importing more from its partners to bring down its big trade surplus.
European Commission President Jean-Claude Juncker put it bluntly: "With France, we have a particular problem ... The French spend too much money and they spend too much in the wrong places. This will not work over time."
The euro fell from six-month highs against the dollar on confirmation of Macron's widely expected victory by a margin of 66 per cent to 34 per cent.
Investors took profit on a roughly 3 per cent gain for the currency since he won the first round two on April 23.
France's economic malaise, especially high unemployment, had undermined the popularity of outgoing Socialist President Francois Hollande to the point where he decided not even to run again as a candidate.
"This year, I wanted Emmanuel Macron to be here with me so that a torch could be passed on," said Hollande, appearing with Macron at the Tomb of the Unknown Soldier at the Arc de Triomphe in Paris to commemorate Victory in Europe Day and the surrender of Nazi forces on May 8, 1945 at the end of World War Two.
Elsewhere in Paris, more than 1,500 people, led by the powerful CGT labour federation, marched in protest against Macron's planned liberalisation of labour laws.
"If he continues with the idea of executive orders in July, that means he will sweep away consultation and dialogue, so there will be a problem one way or another. We shall see," Jean-Claude Mailly, secretary general of the hardline leftist Force Ouvriere union told France Info radio.
On assuming office next Sunday as France's youngest leader since Napoleon, Macron faces the immediate challenge of securing a majority in the June parliamentary election to have a realistic chance of implementing his plans for lower state spending, higher investment and reform of the tax, labour and pension systems.
With the two mainstream parties - the conservative Republicans and the left-wing Socialists - both failing to reach the presidential runoff vote, his chances of winning a majority that supports his election pledges will depend on him widening his centrist base.
The Socialists are torn between the radical left of their defeated candidate Benoit Hamon and the more centrist, pro-business branch led by Manuel Valls, who was prime minister under Hollande.
On Monday, key members of the centrist arm of The Republicans appeared ready to work with Macron despite the party hierarchy calling for unity to oppose the new president and calling those that were wavering "traitors".
"I can work in a government majority," said Bruno Le Maire, a senior Republicans official, who had been an aide of presidential candidate Francois Fillon, and is tipped by some to become the new foreign minister.
"The situation is too serious for sectarianism and to be partisan," he said, later adding that Macron's victory was positive for France.
However, a senior Republican, Christian Estrosi, who had backed Macron and been rumoured to rally behind him, said on Monday he had turned down a ministerial post in order to focus on his home city of Nice.
"I will say things clearly: my only ambition is to serve my city and my region and not to enter the government," Estrosi later told reporters.
Macron's party chief, Richard Ferrand, told a news conference his "En Marche!" movement will now change its name to "En Marche la République" or "Republic on the Move", so as to structure itself more like a traditional party.
He also said the names of Macron's 577 candidates in the legislative elections would be announced this Thursday.
Macron stepped down from the chairmanship of the movement on Thursday and 68-year-old former Socialist government adviser Catherine Barbaroux was named as interim president.
Le Pen, 48, defiantly claimed the mantle of France's main opposition in calling on "all patriots" to constitute a "new political force".
Her tally was almost double the score that her father Jean-Marie, the last far-right candidate to make the presidential runoff, achieved in 2002, when he was trounced by the conservative Jacques Chirac.