Senator Bernie Sanders has apologised to female staff members on his 2016 US presidential campaign who allege they were mistreated by male aides.
"To women in our campaign who were harassed or mistreated, I apologise," the Vermont independent wrote in a statement on Twitter on Thursday.
His apology comes as he contemplates another White House bid under the Democratic banner in 2020.
Several aides have complained of a "predatory culture" in his campaign.
What is the background?
The New York Times reported on allegations by female Sanders aides of mistreatment by male senior staff.
On Wednesday, Politico reported that the deputy national field director for Mr Sanders' campaign had forcibly kissed a younger subordinate in 2016.
"Candidates who allow people like Robert Becker to lead their organisations shouldn't earn the highest office in our government," said the woman, naming the aide.
The unnamed accuser said she never reported the alleged incident because it came on the same day that Mr Sanders' campaign ended after he failed to snatch the Democratic nomination from Hillary Clinton.
She said she felt compelled to speak out after Mr Becker travelled to South Carolina in December on a trip to recruit future campaign workers for Mr Sanders.
Mr Becker denies any harassment, and no criminal charges have been filed.
The allegation comes as dozens of former Sanders campaign workers have signed a letter requesting a meeting with him "to discuss the issue of sexual violence and harassment on the 2016 campaign".
What did Sanders say?
Mr Sanders' Twitter apology comes after he said sorry on CNN last week "to any woman who felt that she was not treated appropriately".
He was criticised for saying he was "a little bit busy running around the country, trying to make the case" for his presidency, and was not aware of the allegations.
To the women on my 2016 campaign who were harassed or mistreated, thank you, from the bottom of my heart, for speaking out. I apologize.— Bernie Sanders (@BernieSanders) January 10, 2019
We can't just talk about ending sexism and discrimination. It must be a reality in our daily lives. That was clearly not the case in 2016. pic.twitter.com/eJtCAGjHZu
Claims of sexual harassment have recently dogged the campaign of Democratic Senator Kamala Harris, who may also enter the White House race.
Senator Harris has said she was "unaware" that a top aide paid a settlement of $400,000 (£314,000) in May 2017 to a woman who sued for sexual harassment.
The California senator's biography, which debuted last week, contains praise for the aide, who resigned after the payout was revealed.