A crucial test of her influence on him will come this week during Mr. Trump’s maiden visit to the United Nations, the organization he has repeatedly pilloried and whose very reason for being — international cooperation — he has dismissed with his promise of “only America first.”
Ms. Haley predicted with confidence at a White House news conference on Friday that Mr. Trump would make “quite an impact” at the world body. What impact she has had on his approach to the world is still unknown.
On Monday, Mr. Trump, who proposed a drastic funding cut to the United Nations, is expected to host an event dedicated to a still-vague, American-led effort to overhaul the organization. On Tuesday, he is scheduled to deliver his address to the General Assembly and have lunch with the secretary general, António Guterres (Mr. Trump had declined for months to schedule a customary meeting), but he is not expected to attend a meeting hosted by Mr. Guterres on climate change. Mr. Trump said in June that he would withdraw the United States from the Paris climate accord, to the dismay of most American allies.
Many credit Ms. Haley for leading what Richard Gowan, a fellow at the European Council for Foreign Relations, called “the administration’s grudging but growing recognition of the U.N.’s significance.”
“It shows Trump engaging with the U.N. rather than bombing it from afar,” added Kenneth Roth, executive director of Human Rights Watch. “Undoubtedly, Nikki Haley gets part of the credit. Destroying the U.N. doesn’t play to the political mainstream.”
At the Friday news conference with Mr. Trump, in remarks that immediately made headlines, Ms. Haley showered her boss with praise. “I personally think he slaps the right people, he hugs the right people, and he comes out with the U.S. being very strong in the end,” she said.
Ms. Haley, 44, the daughter of Indian immigrants, has reinvented herself many times.
Sikh to Methodist. Accountant to politician. Anti-union, anti-abortion Southern Republican star to South Carolina governor well known for pulling down the Confederate battle flag from the State House.
Ms. Haley is nothing if not a deft politician. Her public remarks are addressed to her home crowd and delivered in folksy language, even if they are occasionally flimsy on the facts. She often refers to her staff as #TeamHaley in her Twitter posts, a shrewd bit of personal branding.
The French ambassador to the United Nations, François Delattre, singled out “strong political instincts” as Ms. Haley’s trademark.
Mr. Delattre recalled how Ms. Haley had orchestrated a White House lunch for the other 14 Security Council diplomats and their spouses in April. And he credited her for using her political connections on Capitol Hill to push back against the proposals to radically cut funding for the United Nations.
“She is a master in bringing these very different worlds together, and for that, you indeed need quite exceptional political instincts and skills,” he said.
Behind the scenes, Ms. Haley has pushed back against the nationalists in the Trump camp by lobbying for relatively higher ceilings for refugee resettlement. She has publicly praised Mr. Trump’s decision to abandon the climate agreement, but she has also acknowledged the fact of climate change.
She has said little, publicly, about the president’s handling of the white supremacy rally in Charlottesville, Va., saying on Twitter only that she knows “the pain hate can cause.” But she issued a far more forthright letter to her staff. “Those who march spewing hate are few, but loud,” she wrote. “We must denounce them at every turn, and make them feel like they are on an island and isolate them the same way they wish to isolate others.”
Later, she said in a television interview that she had had “a private conversation” with the president about it.
Her office did not respond to numerous requests for an interview. She is a frequent guest on Sunday morning network television shows, though, and she favors news conferences at the White House, rather than at the United Nations.
She plays to Republican concerns about the United Nations by referring, frequently, to the need to cut “fat” from its budget. She is often the first in the administration to speak out on what she recognizes as the most high-profile foreign policy issues for her Republican base: including Israel and Iran, even if it means glossing over facts.
On Friday, for instance, she asserted that the latest sanctions stop North Korea from earning money by exporting its workers; the sanctions, in fact, stop countries from increasing how many North Korean laborers they can bring in.
In the case of Iran, she said in a speech at the American Enterprise Institute, a conservative research group, that Mr. Trump would be entirely justified if he decided to decertify the nuclear accord, even though the International Atomic Energy Agency has said Iran is complying with its obligations under the deal.
Her biggest success, diplomats say, has been to engage with the United Nations system, rather than to bludgeon it, as many had feared.
“There was a perception that this was a relationship cruising for a bruising,” said Stewart M. Patrick, an analyst at the Council for Foreign Relations. “She has been a skillful politician.”
She has faced tough negotiations. Her efforts to cut the peacekeeping budget met with a great deal of pushback from France, and Ms. Haley had to settle for an approximately $600 million cut to a budget of nearly $8 billion.
She tempered her push to get United Nations forces to disarm Hezbollah in Lebanon even though she had excoriated the force commander of the Interim Force in Lebanon as being “blind” to Hezbollah’s weapons buildup near the Israeli border.
Her broadsides against the United Nations Human Rights Council have been massaged down to more modest calls for change, including for countries to demonstrate, through competitive elections, that they uphold human rights.
Nor did she get the most ambitious North Korea sanctions she fought for after the North tested an extremely powerful nuclear device. She had proposed a full oil embargo; after speedy, intense negotiations with Russia and China, she agreed to a cap of two million barrels of refined petroleum products and a complete ban on natural gas.
That led to an uncomfortable public exchange with her boss.
Mr. Trump described the sanctions as “no big deal.”
So it fell to Ms. Haley to smooth it over. “I think what the president is saying is this is just the beginning of what we can do,” she said.