Senator Bernie Sanders has said he was not aware of allegations of sexism and pay discrimination that occurred during his insurgent campaign for president in 2016 and pledged to “do better” should he run again in 2020.

“I certainly apologize to any woman who felt she was not treated appropriately and, of course, if I run we will do better next time,” Sanders told CNN on Wednesday night.

His comments follow a New York Times report on Wednesday, which described one incident in which a female member of the Latino outreach team said she was told she was supposed to share a bedroom with three men she didn’t know. Another former staffer told the paper that she made $2,400 a month but that a younger male staffer whom she was supposed to manage made $5,000 a month. When she raised the issue her salary was adjusted to achieve parity.

The story was published days after more than two dozen staff members from his 2016 presidential campaign signed a letter seeking a meeting with the senator and his top advisers to address the issue of “sexual violence and harassment on the 2016 campaign, for the purpose of planning to mitigate the issue in the upcoming presidential cycle”, according to Politico, which obtained a copy of the letter.

Asked during an interview on CNN if he was aware of the claims at the time, Sanders replied that he was not.

“I was a little bit busy running around the country trying to make the case,” he said.

Sen. @BernieSanders tells @andersoncooper he had no knowledge of allegations of sexual harassment and pay discrimination against women in his campaign organization during his 2016 bid for the White House, adding, "of course, if I run [again], we will do better next time." pic.twitter.com/2tPlmiYfB3 — Anderson Cooper 360° (@AC360) January 3, 2019

The allegations are surfacing as the Vermont senator weighs a second run for the White House. Some former female staffers say the claims raise questions about whether he is the right candidate to lead the Democrats in the era of #MeToo and after a historic number of female candidates helped propel the party to power in the House of Representatives.

“I’m not going to sit here and tell you that we did everything right in terms of human resources, in terms of addressing the needs that I’m hearing from now that women felt disrespected, that there was sexual harassment that was not dealt with as effectively as possible,” Sanders said. He added that the early days of the campaign were chaotic, as the operation scaled rapidly from a handful of paid staffers to more than a thousand.

Sanders pointed to new policies implemented during his 2018 re-election campaign for Senate that included a hotline run by an independent firm to report incidents of sexual harassment and discrimination and mandatory training for staff and volunteers – measures he described as the “gold standard for what we should be doing”.