White House staff secretary Rob Porter -- a near-constant fixture at President Donald Trump's side -- has resigned from his post, after two ex-wives publicly accused him of domestic abuse.
The White House said Porter denied the allegations and retains the confidence of Trump and his chief of staff John Kelly, but would be leaving his post at an undetermined time.
His resignation comes after reports in the Daily Mail and The Intercept, in which Porter's ex-wives Colbie Holderness and Jennifer Willoughby documented alleged physical and psychological abuse.
A pair of photos showed Holderness with a badly bruised eye, which she claimed was the result of being punched by Porter.
The Intercept reported that the FBI became aware of the allegations when conducting background checks for Porter's security clearance.
Porter is not well known publicly but is often seen on travels with the president outside Washington and in White House meetings.
In recent weeks, he was closely involved in preparations for Trump's address to business leaders in Davos, Switzerland.
The Daily Mail had recently suggested he was in a relationship with Trump's communications advisor Hope Hicks.
"The President and chief of staff have had full confidence and trust in his abilities and his performance," Sanders said Wednesday.
She then read a statement from Porter, in which he said "these outrageous allegations are simply false."
"I took the photos given to the media nearly 15 years ago, and the reality behind them is nowhere close to what is being described."
"I've been transparent and truthful about these vile claims, but I will not further engage publicly with a coordinated smear campaign."
The White House denied suggestions that it ignored security concerns flagged by the FBI.
"Consistent with the practice of past administrations, issues related to an individual's suitability are reviewed through a thorough and lengthy background check process," said Sanders.
"Background checks involve a complex investigation run by intelligence and law enforcement agencies."