WASHINGTON, Oct. 9 (Xinhua) -- A key U.S. lawmaker expressed his concern on Tuesday on Nikki Haley's resignation as U.S. ambassador to the United Nations, which he called another sign of "the Trump Administration's chaotic foreign policy."

U.S. President Donald Trump told reporters earlier in the day that he has accepted Haley's resignation as the country's representative to the UN, making Haley the latest senior official to exit the Trump administration.

"Today's announcement that Ambassador Haley is resigning is yet another sign of the Trump Administration's chaotic foreign policy," said Bob Menendez, the ranking Democrat on the Senate's Foreign Relations Committee, in a statement.

"I am deeply concerned about the leadership vacuum she leaves and the national security impact of her departure at this time of continued disarray for the Administration," added the New Jersey Senator in the statement released on Twitter.

Trump said on Tuesday that he was going to name a new U.S. ambassador to succeed Haley within two or three weeks.

Haley, 46, was confirmed as the U.S. ambassador to the UN days after Trump's inauguration in January 2017. She has been seen as one of Trump's most trusted advisers.