Hope Hicks, one of President Donald Trump's longest-serving aides, is resigning from her job as White House communications director, White House press secretary Sarah Sanders said on Wednesday.
Ms Sanders told reporters the timeline for Hicks' departure was unclear.
She said her departure was not related to her testimony to a congressional committee on Tuesday about a probe into Russian meddling in the 2016 presidential election.
"There are no words to adequately express my gratitude to President Trump. I wish the President and his administration the very best as he continues to lead our country," Ms Hicks said in a written statement.
Her pending resignation follows a nine-hour closed-door testimony on Tuesday where Ms Hicks, 29, acknowledged she had told what amounted to white lies for US President Donald Trump, according to the New York Times.
Despite the claims during the testimony, which was part of the House Intelligence Committee's Russia investigation, Ms Hicks claimed she hadn't had to lie about substantive issues for Mr Trump.
President Donald Trumpin the Oval Office of the White House January 24, 2017 in Washington, DC with White House Communications Director Hope Hicks (middle). Source: Getty Images North America
But White House spokesperson Hogan Gidley slammed the claims as "false".
Ms Hicks declined to answer any questions on her time in the White House making her the latest senior official to stay silent on Mr Trump's 2016 election.
Former White House chief strategist Steve Bannon and former Trump campaign manager Corey Lewandowski both made similar claims before the committee.
Ms Hicks, however, did answer a few questions about the presidential transition despite initially claiming she would not discuss the events.
The 29-year-old former model came under fire during her role as an adviser after she reportedly helped craft a controversial statement on the 2016 meeting between members of the Trump campaign and a Russian lawyer at Trump Tower.
At the time, Donald Trump Jr initially released a statement claiming a meeting took place with a Russian lawyer to discuss US policy on Russian adoptions - rather than allegedly being offered damaging information about Hilary Clinton.
It was claimed Ms Hicks and Mr Trump took part in drafting the initial statement on the meeting aboard Air Force One.
Since the statement, Mr Trump Jr has faced growing questions about contact with Russians during the 2016 presidential election.
Top officials and advisers who have resigned or been dismissed under Trump
Stephen Bannon - Chief strategist
Mr Trump's former chief strategist, Stephen Bannon, lasted less than seven months after he was reportedly removed by the administration. However, a New York Times report claims Mr Bannon had submitted his resignation to the president before he was stood down.
Sean Spicer - Press secretary
The embattled former press secretary lasted a turbulent six months after he resigned over Mr Trump's hiring of Anthony Scaramucci as communications director, according to reports.
White House Press Secretary Sean Spicer reacts to reporters' questions in the Brady Press Briefing Room at the White House January 30, 2017 in Washington, DC. Source: Getty Images North America
Michael Flynn - National security adviser
Mr Flynn lasted only three weeks in the White House after Mr Trump asked for his resignation following claims he misled the vice president.
Reince Priebus - Chief of staff
Lasting six months, Mr Trump asked for Mr Priebus' resignation to replace him with John Kelly.
Anthony Scaramucci - Communications director
Mr Scaramucci was fired from the White House after 10 days following a verbal tirade during an interview.
Hope Hicks - White House Communications director
Hope Hicks is set to resign for unknown reasons.
- With Reuters
