Outgoing U.S. Ambassador to the United Nations Nikki Haley on Tuesday dismissed speculation she is open to challenging President Trump for the Republican presidential nomination in 2020.

"For all of you that are going to ask about 2020, no, I am not running for 2020. I can promise you what I'll be doing is campaigning for this one," Haley told reporters gathered in the Oval Office. "I look forward to supporting the president in the next election."

[READ: Nikki Haley's letter of resignation]

Haley has been touted as a future Republican presidential candidate given her track record as South Carolina governor from 2011 to 2017. She has additionally impressed critics with her job representing the U.S. at the U.N. after some expressed doubt she had the foreign policy credentials for the role.

During her White House visit Tuesday, Haley said she was leaving the Trump administration because she believed in "term limits."

"I think you have to be selfless enough to know when you step aside and allow someone else to do the job," she said. "So thank you, Mr. President. It's been an honor of a lifetime."

Haley is expected to relinquish her position leading the country's U.N. mission by year's end.

[Related: Ivanka Trump to replace Nikki Haley? Speculation runs rampant after UN ambassador resigns]