At first glance, Jill Biden’s work on her trips overseas appears to be rooted in the traditional duties of first ladies: She has cheered on American Olympians in Tokyo, made a secret trip to Ukraine to meet with the country’s first lady and attended the royal wedding of the crown prince of Jordan.
But in a host of speeches delivered overseas, including in Namibia and France, she has also used her platform for more political purposes, including making her case that President Biden has promoted democracy and revitalized global relationships strained by former President Donald J. Trump.
In Paris on Tuesday, the first lady’s presence was a reminder, as the 2024 presidential campaign heats up, that Americans may again be choosing between the two men. Dr. Biden was there to deliver remarks for the official return of the United States to UNESCO, several years after the Trump administration pulled the country — and its funding — from the group.
She was also there to deliver a White House message that Mr. Biden had united allies against what she called “Putin’s unjust war” in Ukraine.
“When my husband, President Biden, took office two and a half years ago, he made a promise to the American people,” Dr. Biden said, “that he would rebuild the systems that were broken and fortify our institutions, that he would work to bring divided communities back together, that he would put us on a path to a better, brighter future while restoring our leadership on the world stage. And he did.”
She told a crowd of hundreds outdoors at the UNESCO headquarters in central Paris that her husband “understands that if we hope to create a better world, the United States can’t go it alone, but we must help lead the way.” The dark-gray sky above her looked ominous, and as she spoke, rain began to fall.
During his time in office, Mr. Biden has cast the future as a stark battle between democratic and autocratic forces. But in practice, he has been more nuanced.
Like Mr. Trump, he has embraced a working diplomatic relationship with Saudi Arabia despite his complaints about the country’s approach to human rights, and he has imposed tough restrictions on asylum seekers who cross the border the United States shares with Mexico.
Still, his administration has worked to reposition the United States as a more collaborative partner than it was under Mr. Trump, who pulled out of several international accords and at one point threatened to pull the United States from NATO. For her part, Dr. Biden’s role has been to promote her husband, if not the details of his policies.
“She brings a polish and a warmth and a compassion to the job unrivaled by any first lady I know of, particularly as it relates to Europe,” Mark Gitenstein, a longtime Biden ally and the ambassador to the European Union, said in an interview. Mr. Gitenstein, who has known the first lady since the 1970s, said Dr. Biden has evolved from a reluctant public figure to a first lady eager to validate her husband’s credentials.
Mr. Biden has low approval ratings domestically, but recent polling has found support for his approach internationally: Views of the president and of U.S. leadership have remained stable or improved since Mr. Biden was elected, according to a survey of 23 countries published in June by the Pew Research Center.
The Biden administration has rejoined several global organizations and pacts that Mr. Trump pulled out of, including the World Health Organization, the Paris climate agreement, the United Nations Human Rights Council and UNESCO. Audrey Azoulay, the director general of UNESCO, told Dr. Biden in a meeting on Tuesday that “it’s important to see the U.S. back at the table.”
UNESCO, or the United Nations Educational, Scientific and Cultural Organization, is best known for designating World Heritage sites, more than 1,150 of them since 1972. They include Yosemite National Park in California, Angkor in Cambodia and the Stone Town of Zanzibar. The organization also keeps an “intangible cultural heritage” list of humanity’s most worthy creations — like the French baguette.
The United States had also withdrawn from the agency in 1984, during the Cold War, because the Reagan administration deemed it too susceptible to Moscow’s influence and overly critical of Israel. President George W. Bush pledged in 2002 to rejoin the organization partly to show his willingness for international cooperation in the lead-up to the Iraq war. Citing bias against Israel, the Trump administration again pulled out in 2017.
During her trip to Paris, Dr. Biden and her daughter, Ashley Biden, toured the Élysée Palace as the guests of Brigitte Macron, the French first lady. Mrs. Macron is expected to join Dr. Biden on a tour of northern France on Wednesday, according to Dr. Biden’s staff. The first lady is scheduled to visit Mont-Saint-Michel, a UNESCO World Heritage site and a Gothic-style Benedictine abbey on an island off the coast. Dr. Biden is also scheduled to visit the Brittany American Cemetery to honor soldiers who were killed during World War II.
This year Dr. Biden has also traveled to Mexico, Kenya, Namibia, Canada, Japan, Jordan, Egypt and Morocco. Sometimes, she is alongside her husband for diplomatic summits, as she was in Mexico, Canada and Japan. But more often than not, she has been the person he chooses to represent him: In May, she traveled to Britain to attend the coronation of King Charles III.
In Paris, she spoke, as she often does, of her long career as an educator, and of the importance of lifting up women and girls, though Dr. Biden’s policy portfolio does not include ambitious plans for education access or elevating gender issues.
“Pursuing legislation or pushing a legacy-defining initiative is not the kind of activist role of first lady she wants to play,” said Michael LaRosa, her former press secretary. “In many ways, she’s much more comfortable as a permanent campaign spouse because the objective of every speech, event or trip, whether it’s political or official, is in service of her husband’s agenda and lifting up his achievements.”
Some of her trips have been at the behest of foreign leaders.
At the Group of 7 summit in Cornwall, England, in 2021, Prime Minister Yoshihide Suga of Japan and his wife approached her as she was climbing out of a motorcade and appealed to her to attend the Olympic Games during the pandemic, according to Mr. LaRosa.
Masked, she cheered on the athletes from the bleachers.
When she is on a plane, she and her aides work on speeches, look over her news coverage and talk over glasses of wine. Dr. Biden also takes cat naps, according to Vanessa Valdivia, her press secretary.
Aurelien Breeden contributed reporting.