WHITE HOUSE - U.S. Ambassador to the United Nations Nikki Haley is resigning.

"It has been an honor of a lifetime," said Haley, sitting alongside President Donald Trump in the Oval Office, where on Tuesday they announced her pending departure. "I'm not leaving until the end of the year."

"We will miss you," Trump said to Haley. "You have done a fantastic job."

Thanking Haley for her service, Trump characterized the diplomat as "very special to me" and someone whom he had teamed with and "solved a lot of problems," citing, in particular, issues with Iran and North Korea.

"Hopefully, you'll be coming back at some point," added the president, saying "you can have your pick" of other jobs in his administration.

"I don't have anything set on where I'm going to go," said Haley.

The former governor of South Carolina has been seen by some as a relatively moderate voice in Trump's Cabinet.

WATCH: Haley resigns

?Her appointment as ambassador to the U.N. was seen as a surprise because she had been viewed as a critic of Trump's confrontational style during the 2016 presidential campaign. She also has been a proponent of free markets and global trade, in contrast to the president's "America First" policies.

"Countries may not like what we do, but they respect what we do," Haley said Tuesday, summarizing her tenure as Trump's envoy to the world body.

Speaking to reporters later in the day, Trump was asked if his daughter, Ivanka Trump, who works in the White House as an adviser to her father, could succeed Haley.

Ivanka Trump "would be dynamite, but then I would be accused of nepotism if you can believe it," he said. "I'm not sure there's anybody more competent in the world."

Ivanka Trump tweeted later she knows her father will pick a "formidable replacement," but that she will not be taking Haley's place.

President Trump also mentioned Dina Habib Powell, an Egyptian-born fluent Arabic speaker who was previously his deputy national security adviser for strategy.

“Dina’s certainly a person I would consider and she’s under consideration,” he said.

Proud of administration role

Haley responded recently to an anonymous opinion article in The New York Times by an unnamed senior official who claimed to be part of a "resistance" inside the Trump administration to thwart parts of the president's agenda and his "worst inclinations."

Haley, writing in The Washington Post, said that she was proudly serving in Trump administration and "I enthusiastically support most of its decisions and the direction it is taking the country."

As ambassador to the world body, Haley had clashed with her first immediate boss in the Trump administration, Rex Tillerson, who was fired by the president in March.

U. S. Secretary of State Mike Pompeo, with U.S. Am FILE - U.S. Secretary of State Mike Pompeo, with U.S. Ambassador to the United Nations Nikki Haley, speaks to reporters at U.N. headquarters, July 20, 2018. FILE - U.S. Secretary of State Mike Pompeo, with U.S. Ambassador to the United Nations Nikki Haley, speaks to reporters at U.N. headquarters, July 20, 2018.

Current Secretary of State Mike Pompeo praised Haley "for the good work that she's done," saying she has been a great partner.

"She has been unique in this administration, not because she's pushed a strong U.S. agenda, but in showing that to accomplish our goals we need to sit down with other countries and work in concert with allies and friendly countries," Richard Boucher, a Brown University Watson Institute senior fellow and former assistant secretary of state, told VOA. "Secretary Pompeo now takes this approach as well. Others have tended to bluster and think that's how to get what we want."

Former diplomat Mintaro Oba, who spent three years on the Korea desk at the State Department, said he did not see Haley's departure prompting any major changes for most policies, including those related to North Korea.

"A bigger question mark is how the United States will replace the relationships and trust she built with others at the U.N. and how that will impact key U.S. initiatives in the U.N. Security Council, like the North Korea pressure campaign," Oba told VOA.

Trump agenda

Trump has been a loud and frequent critic of the United Nations, and Haley pushed his agenda against what he saw as mismanagement and biases at the world body.

U.N. Secretary-General Antonio Guterres described his relationship with Haley as "very productive and strong," lauding her for promoting "constructive ties between the United Nations and the United States, showing the value of the United Nations."

Israeli Prime Minister Benjamin Netanyahu, on Twitter, thanked Haley for leading what he termed "the uncompromising struggle against hypocrisy at the U.N., and on behalf of the truth and justice of our country."

As governor of South Carolina, Haley came to national prominence for taking down the flag of the Confederacy at the State House in Columbia. The flag is a symbol of the losing Southern side during America's mid-19th century Civil War.

WATCH: Haley Says She's Not Running for President

Haley, 46, whose parents emigrated from India, is one of six women in Trump's Cabinet and has been regarded by some as a potential Republican Party presidential contender.

"No, I'm not running for 2020," Haley told reporters Tuesday, adding that she would be campaigning for Trump's re-election in the next presidential election.

Heritage Foundation fellow Brett Schaefer, who focuses on the U.N., said, "I think she's absolutely a star in the making. She's relatively young. She has a bright political future ahead of her, in my opinion."