WASHINGTON (BLOOMBERG) - First lady Melania Trump's chief of staff, Ms Stephanie Grisham, resigned on Wednesday (Jan 6), citing frustration over the mobs who stormed the US Capitol to disrupt congressional certification of President-elect Joe Biden's victory, according to people familiar with the matter.

Ms Grisham confirmed that she's resigning but didn't respond to questions about the reason.

It's not unusual for members of the White House staff to depart before a change in administrations but the people said she'd been considering leaving for months and that the violence was a deciding factor.

Wednesday's attack on the Capitol by President Donald Trump's supporters was an embarrassment to some White House officials, including Ms Grisham, the people said.

"It has been an honour to serve the country in the @WhiteHouse," she tweeted. "I am very proud to have been a part of @FLOTUS @MELANIATRUMP mission to help children everywhere, & proud of the many accomplishments of this Administration."

Mr Trump told his supporters who broke into the Capitol as the two houses of Congress had gathered to certify the Electoral College vote to "go home now", hours after they marched on the Capitol at his urging and stormed the building.

Ms Grisham served as press secretary for Mr Trump until she was replaced in April by Kayleigh McEnany as part of a reshuffle of the White House communications operation after Mark Meadows came in as Mr Trump's latest chief of staff.