Challenged by the extreme right and perhaps more vulnerable than at any time in his presidency, Emmanuel Macron of France sought renewed momentum on Thursday through a sweeping speech on the need for a more assertive Europe, a theme that he has pressed with urgency since Russia’s invasion of Ukraine in 2022.

The nearly two-hour speech reflected Mr. Macron’s conviction that only a reinforced and “sovereign” European Union — a “Europe power,” as he puts it — can save the continent from strategic irrelevancy in an unstable world that is dominated by the United States and China and confronting wars in Europe and the Middle East.

“We must be lucid about the fact that our Europe is mortal,” Mr. Macron declared before an audience of government ministers, European ambassadors and other dignitaries. “It can die. It can die and whether it does depends entirely on our choices.”

The speech, at the Sorbonne University in Paris, was a follow-up to one that Mr. Macron gave in the same location in September 2017. Then, Mr. Macron discussed the future of Europe and the European Union as a young, recently elected and disruptive president still enjoying a political honeymoon. Today, without an absolute majority in Parliament, and with his popularity falling after seven years in office, he has become a divisive figure and has struggled over the past two years to give direction to his second term.

Coming less than two months before elections to the European Parliament on June 9, Mr. Macron’s decision to speak out was widely seen as a bid to boost his centrist Renaissance party, which is placing a distant second in the latest polls behind the far-right National Rally party led by Jordan Bardella. Mr. Macron’s party is polling at about 17.5 percent of eligible voters; Mr. Bardella’s has about 30 percent.

Mr. Macron described a world at “a turning point,” in which a Europe that could no longer depend on America for its security, on Russia for its energy and on China for its industrial production must become more strategically autonomous, technologically innovative and militarily resilient.

“We are too slow and not ambitious enough,” he said, proposing that only through “power, prosperity and humanism” could Europe set out a distinctive model for the world. It should “never be a vassal of the United States,” he said, without making any radically new proposals.

There have been significant advances toward greater European integration since Mr. Macron’s first speech, which was in some ways prescient. The Covid pandemic saw Germany break a longstanding taboo and back the issuing of European joint debt, and the war in Ukraine has spurred increased European spending on defense, something Mr. Macron has long called for to reduce reliance on American military power.

But, always impatient with what he considers lazy thinking, as when he described NATO as suffering from “brain death” in 2019 because it had not adjusted to a changed world, Mr. Macron has also irked some of his European partners with his bold declarations. Not everyone in Europe is convinced that it is Mr. Macron’s role to lead the 27-member union to a different future.

Recently, the always difficult relationship between Mr. Macron and Chancellor Olaf Scholz of Germany has been roiled by differences over the war in Ukraine and how to manage the United States. Mr. Scholz was incensed by Mr. Macron’s recent suggestion that the deployment of Western troops in Ukraine could not be ruled out, a statement the president said on Thursday that he “stands by absolutely.”

“The essential condition of our security is that Russia not win its war of aggression against Ukraine,” Mr. Macron said.

Mr. Macron reiterated his support for the creation of a European “rapid deployment” force of about 5,000 military personnel, which was outlined by the E.U. in 2022 as a way to respond to external crises. It is expected to be fully operational in 2025. He also expressed support for the creation of a “European military academy” to improve coordination between European armies. E.U. member states, he said, should prioritize buying European military equipment over foreign materiel.

These are familiar themes from the president, who has struggled to overcome an image of aloofness. It was far from clear that his lofty visions, at a time of economic difficulty for many French people, would do anything to dent the popularity of Mr. Bardella, the far right’s 28-year-old prodigal son.

The longtime barrier against the far right coming to power, built around the broad conviction that the National Front (now the National Rally) was a danger to the republic, has collapsed as the party has become the largest single opposition force in Parliament.

“Our opponent in this European election is Emmanuel Macron, and I am telling French people that what we have to achieve on June 9 is set limits for the president of the republic,” Mr. Bardella said in a televised appearance on Thursday, before Mr. Macron’s speech. Mr. Bardella’s themes — anti-immigration rhetoric, the need for greater security and the fight against inflation — have resonated with an anxious France.

Mr. Bardella is the protégé of Marine Le Pen, the perennial far-right candidate for the presidency. His popularity has increased the chances that she may succeed Mr. Macron, who is term-limited, in 2027, or even that he become a presidential candidate himself.

Clearly taking aim at the extreme right, Mr. Macron said that “liberal democracy is not a given” and that the rule of law, an independent press, free universities, the rights of minorities and the separation of powers were being “denied” in too many European countries. He celebrated Poland as an example of an E.U. member turning its back on illiberalism, after its recent election that saw a centrist victory over the governing nationalist party.

Mr. Macron also said that he hoped to see the right to abortion enshrined in the European Union’s charter of fundamental rights; France last month became the first country in the world to protect access to abortion in its Constitution.

Aides to Mr. Macron insisted that the Sorbonne was not a campaign stop, arguing that Mr. Macron wanted to influence the European Union’s overarching strategic agenda for the next five years, which is expected to be decided by E.U. leaders after the June elections.

Speaking on condition of anonymity, in line with French government practice, they said that the crises that have gripped the world since his first speech in 2017 demonstrated that Mr. Macron was right in his insistence that Europe needs to be the master of its own destiny by shaking off technological and industrial dependencies, especially on China and the United States.

Anxiety is widespread in Europe that the American presidential election in November could result in a victory for former President Donald J. Trump, whose “America First” program and skepticism over NATO have increased concerns over European military and strategic dependency on the United States. For Mr. Macron, these developments have been a form of vindication of his seven-year-old warnings.

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