Nikki Haley has resigned as U.S. ambassador to the United Nations and will leave her position at the end of the year.

Haley, considered as a possible future presidential candidate, told reporters on Tuesday that she will not be pursuing a presidential run in 2020.

“No, I am not running for 2020,” she said alongside President Donald Trump at the Oval Office.

Trump showered praise on Haley after accepting her resignation, saying that she had “done a fantastic job” and referring to her as a “great friend.” Her successor will be named within two or three weeks, he said.

Haley cited the difficulty of shifting immediately from six years as governor of South Carolina to two years as U.N. ambassador.

“It’s been eight years of intense time, and I’m a believer of term limits,” she said.

The daughter of immigrants from India and one of only a few women in Trump’s cabinet, Haley positioned herself as a moderate voice in the Trump administration, touting reform of the U.N. over withdrawal from it.

Using the international organization as a platform to trumpet American interests, Haley was an outspoken critic of countries such as Iran, Syria and Russia. During her first news conference at the U.N., she announced that the U.S. would be “taking names” of countries “that don’t have our back.”

Haley praised the administration’s efforts throughout her two-year tenure.

“Now the United States is respected,” she said Tuesday. “Countries may not like what we do, but they respect what we do. They know that if we say we’re going to do something, we follow it through.”

She also hailed the U.S.-led effort that cut $1.3 billion from the U.N.’s budget, the three North Korea sanctions resolutions adopted under Trump’s term as well as the decision to move the U.S. Embassy to Israel from Tel Aviv to Jerusalem.

“The U.S. is strong again, and the U.S. is strong in a way that should make all Americans very proud,” Haley said.

Despite her promotion of Trump’s “America first” policies, many diplomats saw her as a buffer between some of the hard-liners in Washington, and at times she appeared to break from the administration. Haley regularly slammed Moscow at U.N. Security Council meetings, even as Trump moved toward a warmer relationship with his Russian counterpart, President Vladimir Putin.

Haley is one of the most popular members of Trump’s administration. A Quinnipiac University poll in April surveying the administration’s approach toward North Korea found that she had a 63% approval rating, highest among members of Trump’s national security team.