"Countries may not like what we do, but they respect what we do", Haley said.
During an Oval Office meeting, Haley beat back the idea that she might be preparing a 2020 primary run against Trump, saying that she will campaign with the president.
Dina Powell, a former Goldman Sachs executive who served in the Bush White House and State Department, and later as Trump's Deputy National Security Advisor, was one of the first names to be uttered as the next possible United Nations ambassador.
Haley has handled a number of contentious issues during her time at the UN, including withdrawing the US from the UN Security Council.
Haley, a former governor of SC, had been an early and frequent critic of Trump, so when he named her the envoy to the world body weeks after his election in November 2016, the appointment was seen as an olive branch.
Haley cited Trump's tough trade policy, his decision to leave the Iran nuclear deal and move the U.S. Embassy in Israel to Jerusalem, which infuriated many allies and regional partners.
"I don't agree with the president on everything".
The feel-good nature of her resignation was markedly different from other departures from the Trump Cabinet.
She was also spotted in a photograph with Haley, visiting her in SC this past weekend. The official noted that their conversation coincided with the appointment of Mike Pompeo as secretary of state and John Bolton as national security adviser.
Earlier this year, Haley, 46, told Reuters that, "Every day I feel like I put body armor on", to protect US interests at the United Nations.
"I don't get confused", Haley said in a sharply-worded rejoinder to the West Wing.
Haley, 46, was the senior most Indian-American official in the Trump administration.
U.N. Ambassador Nikki Haley plans to resign, The Associated Press has learned. "I am saddened that she is leaving the administration, but so grateful for her service".
Before being chosen as Trump's ambassador, Haley, 46, served as governor of the state of SC - the first woman to hold the post. "They know that if we say we're going to do something, we follow it through", she said.