But if Mr. Macron’s party does not win enough seats in the legislative elections, the Assembly could essentially force him to choose another prime minister.
The two mainstream parties — the Socialists and the Republicans — hope to reassert themselves in the legislative elections, as does the far-right National Front, led by Ms. Le Pen. The movement of the far-left presidential candidate Jean-Luc Mélenchon also hopes to do well.
In short, the parliamentary elections could easily be a five-party affair, a reflection of the electorate’s fragmentation and a loss of faith in mainstream parties.
Sylvie Goulard, a centrist member of the European Parliament who supports Mr. Macron, told the CNews channel on Monday that Mr. Macron would go to Berlin for his first trip outside France, but she added he might first visit French troops posted abroad.
Chancellor Angela Merkel of Germany congratulated Mr. Macron on his “spectacular” victory on Monday.
“He carries the hopes of millions of French people, and of many people in Germany and the whole of Europe,” Ms. Merkel said at a news conference. “He ran a courageous pro-European campaign, stands for openness to the world and is committed decisively to a social market economy.”
Mr. Hollande has privately complained that he was betrayed by Mr. Macron, his onetime protégé, but he showed no signs of bitterness on Monday.
Mr. Macron resigned as economy minister in August to clear the way for a run for president. In December, Mr. Hollande, whose popularity plummeted during his five-year term, said that he had decided not to seek a second term.
“It is true that he followed me for many years, but afterward he freed himself,” Mr. Hollande said of Mr. Macron on Monday. “He wanted to propose a project to the French. It is up to him now, strengthened by the experience he has acquired with me, to continue his march. I wish him every success.”
President Vladimir V. Putin of Russia joined a chorus of world leaders, including President Trump, who have congratulated Mr. Macron.
“The citizens of France have trusted you with leading the country at a difficult time for Europe and the whole world community,” Mr. Putin said in a statement. “The growth in threats of terrorism and militant extremism is accompanied by an escalation of local conflicts and the destabilization of whole regions. In these conditions it is especially important to overcome mutual mistrust and unite efforts to ensure international stability and security.”
Mr. Putin made no mention of the widespread reports that agents linked to Russia had tampered with the Macron campaign, just as they hacked the Democratic Party and the campaign of Hillary Clinton in the United States last year.
Mr. Macron’s campaign said on Friday evening that his party been the target of a “massive and coordinated attack,” after a trove of stolen campaign documents and emails was published online.
A New York-based cyberintelligence consultancy, Flashpoint, said there were indications that a hacker group with ties to Russian military intelligence had been behind the attack. Mr. Putin and his spokesman have repeatedly denied interfering in the elections of foreign countries.
The National Front in France was regrouping after the presidential race. The latest results showed that Ms. Le Pen won 33.9 percent of those who voted — less than expected, but by far the party’s strongest showing in a presidential election. (Ms. Le Pen’s father, Jean-Marie Le Pen, won 17.9 percent in the 2002 runoff against President Jacques Chirac, who was easily re-elected.)
Echoing Ms. Le Pen’s concession speech, Nicolas Bay, the National Front’s secretary general, said that “a new divide is emerging: the patriots face the globalists.”
He said it was “obviously necessary for the National Front to transform itself.” Asked whether the party’s name would change, as Ms. Le Pen has hinted, he suggested that such a move was likely.
“I think it can be one of the means to be even more unifying and to live up to what the French are waiting for,” he said. “This decision will not be made in the next few weeks, but rather in the coming months.”