Sylvain Crepon, a French sociologist and a leading expert on Le Pen's National Front (FN), said the party "has managed to implant its identity politics across the political spectrum". Macron is already looking the part.
It will be a short honeymoon for French President-elect Emmanuel Macron.
France's far-right National Front party is gearing up for a name change - but not a makeover of its ideas - after its decisive loss to centrist Emmanuel Macron.
The U.S. economy's weak performance at the start of the year should slow Federal Reserve plans for further rate increases, now broadly expected to resume at the central bank's June meeting, St. Louis Federal Reserve bank president James Bullard said on Monday.
Current President Francois Hollande spoke of his "emotion" at the event but Mr Macron did not say a word.
Mainstream parties on the left and right that were frozen out of Sunday's runoff in a first for modern France, also are regrouping, aiming to clip Macron's wings and impose their political agenda, via parliament, on his five-year term. The worst-case scenario for him would be a strong parliamentary majority for his opponents, dictating his choice of prime minister and limiting his presidency.
In addition, Le Pen had been vocal about a possible Frexit earlier - she had even been dubbed "Madam Frexit" in the past.
Multi-billion-dollar arms deal with Saudi Arabia
After leaving the Middle East, the president will meet Pope Francis at the Vatican. "Tolerance is the cornerstone of peace", Mr. Saudi Arabia's foreign minister Adel al-Jubeir also confirmed that an upcoming visit to the kingdom by U.S.
A protest Monday in Paris against Macron's planned reforms drew several thousand people.
Saudi Arabia's OPEC governor said on Friday there was an emerging consensus among member and non-member countries on the need to extend the output-control agreement beyond June to help clear the supply glut.
He also promised to work to unify France after a bruising presidential campaign and serve the country "with love". "But fundamentally, I don't see any changes in the euro's uptrend", said Kazushige Kaida, head of foreign exchange at State Street in Tokyo.
En Marche's 577 candidates will be announced by Thursday.
The vote was the best electoral result ever obtained by her National Front party, which was established in the 1970s by her father, the Holocaust denier Jean-Marie Le Pen, who has multiple convictions for inciting racial hatred against Jews.
More congratulations rolled in from world leaders.
On the financial front, European stock markets edged down in early trading as investors had been widely expecting Macron's victory. Other indexes across Europe also dipped, while the euro, which briefly hit a six-month high above $1.10 overnight, was down 0.7 per cent at $1.0924.
Over in Australia, the ASX 200 (ASX:.AXJO) was higher by 0.69 percent, driven largely by its energy and materials sub-indexes which were up 1.87 percent and 1.63 percent respectively.