Harris Attacks Trump, Saying ‘We Are Not Going Back’

President Emmanuel Macron of France sent Mr. Biden a letter on Monday that praised “the courage, the spirit of responsibility and the sense of duty” that led Mr. Biden to drop out of the race, according to Mr. Macron’s office.

“At a time when we have just celebrated the 80th anniversary of the D-Day landings, I hope that this spirit of partnership between the two sides of the Atlantic will continue to drive the longstanding relations between our two countries,” the letter said. Mr. Macron, a centrist, has had a tense history with Mr. Trump.

Mr. Biden and Mr. Macron have worked closely on several fronts, including supporting Ukraine in its war with Russia, though they have diverged on the Israeli military campaign in Gaza. France has backed an effort at the International Criminal Court to secure arrest warrants for the leaders of Israel and Hamas; Mr. Biden has condemned the effort, saying there is no comparison between Israel and Hamas.

Still, Mr. Biden has often been at odds with Israel’s leader, Prime Minister Benjamin Netanyahu, over the war in Gaza. Mr. Biden has pushed for a more restrained military campaign and warned Mr. Netanyahu that American arms shipments to Israel could be threatened by continued civilian deaths in Gaza.

Mr. Netanyahu, who was scheduled to arrive in Washington on Monday and to address Congress later in the week, told reporters that he planned to thank the president for “the things he did for Israel in the war and during his long and distinguished career in public service.”

In Russia, which united much of Europe when it invaded Ukraine, President Vladimir V. Putin had said earlier this year that he would prefer Mr. Biden over Mr. Trump, describing Mr. Biden as predictable. Some analysts, however, had said Mr. Putin may have sought to hurt Mr. Biden’s standing with U.S. voters by granting him an unwanted endorsement.

A spokesman for Mr. Putin, Dmitri S. Peskov, said that Ms. Harris had made statements that were “quite unfriendly toward” Russia. But Mr. Peskov added that the Kremlin did not believe that the vice president presented “a plus sign or a minus sign” in the relationship between the United States and Russia.

He expressed little surprise at Mr. Biden’s withdrawal, saying that “events in the United States in recent years have taught us not to be surprised by anything.”

Mr. Trump, who has sometimes praised Mr. Putin, has claimed that Russia would not have invaded Ukraine in 2022 if he had been president at the time.

Ms. Harris has accused Russia of committing crimes against humanity in Ukraine and said that Russia must be held accountable for “barbaric” behavior in the war. She has seemed to be in lock step with Mr. Biden. In a speech in 2022, Mr. Biden declared in an apparently unscripted moment that Mr. Putin could not “remain in power.”

President Volodymyr Zelensky of Ukraine said in a statement on Sunday that he would always be grateful for Mr. Biden’s leadership during the conflict and that the president’s decision to drop out was “tough but strong.”

“He supported our country during the most dramatic moment in history, assisted us in preventing Putin from occupying our country, and has continued to support us throughout this terrible war,” Mr. Zelensky said.

Across Europe, leaders hailed Mr. Biden’s decision to remove himself from the campaign. But they stopped short of backing Ms. Harris, who was rapidly consolidating Democratic support after she received Mr. Biden’s endorsement.

Prime Minister Keir Starmer of Britain, a center-left leader whose Labour Party won a landslide election victory this month, said in a statement that Mr. Biden’s career was “remarkable.” The president made a decision “based on what he believes is best for the American people,” Mr. Starmer added.

Prime Minister Pedro Sánchez of Spain described Mr. Biden’s decision as dignified and courageous. And the German chancellor, Olaf Scholz, who had vouched for Mr. Biden’s mental acuity in recent days, said Mr. Biden had served an essential role in strengthening NATO and reinforcing trans-Atlantic cooperation.

Mr. Trump, who regularly disparages NATO, is viewed with wariness across Europe but has a close ally in Viktor Orban, the far-right prime minister of Hungary. Mr. Orban has said he believes the former president survived an assassination attempt this month because God had a plan for him to bring peace to the world.

In countries that have strained relationships with the United States, the responses to Mr. Biden’s exit varied in tenor.

Iran said Monday that it was not concerned about a change in American leadership and that its priority was a full restoration of the 2015 nuclear deal. A spokesman for Iran’s Foreign Ministry, Nasser Kanaani, said that a “change in America’s hostile attitude toward Iran” would be needed to alter the relationship between the two countries.

During his presidency, Mr. Trump pulled the United States out of the nuclear deal, which had been reached by President Barack Obama when Mr. Biden was vice president. As president, Mr. Biden has struggled to revive the deal.

After his exit from the race, Mr. Biden also received a warm reaction from a seemingly unlikely source in South America.

President Nicolás Maduro of Venezuela, an autocratic leader who is facing an election on Sunday and has long had an antagonistic relationship with the United States, offered a conciliatory message.

“President Biden, I believe, has made the most sensible and correct decision,” Mr. Maduro said in a video he published on social media.

The last three U.S. presidents have been aligned in using tough penalties to respond to corruption, human rights abuses and anti-democratic measures in Venezuela. Diplomatic relations between the United States and Venezuela have been largely frozen since 2019.

But Mr. Biden’s administration has pursued private dialogue with Venezuelan government officials. And Mr. Maduro did not appear to hold any grudges in responding to Mr. Biden’s exit, wishing him “health and long life.”

President Luiz Inácio Lula da Silva of Brazil, a leftist, also had words of praise for Mr. Biden. On social media, Mr. Lula said that he “really likes and respects” Mr. Biden. He did not indicate a preference in the U.S. election.

Reporting was contributed by Anton Troianovski, Farnaz Fassihi, Genevieve Glatsky, Isayen Herrera and Aurelien Breeden.