"I thank them, from the bottom of my heart, for speaking out", Sanders wrote in a statement. "The allegations speak to unacceptable behavior that must not be tolerated in any campaign or any workplace".
He apologized "to any woman who felt that she was not treated appropriately, and of course if I run, we will do better next time", but went on to say that he was unaware of the allegations because he "was a little bit busy running around the country trying to make the case".
In his statement Thursday, Sanders admitted his 2016 campaign's "standards and safeguards were inadequate".
According to POLITICO, Mr. Becker "oversaw Sanders' Iowa campaign, then helped lead his efforts in Michigan, California and NY as deputy national field director" and has reportedly started calling former staffers to prep for Sanders' potential 2020 run over the past few months. When asked if he was aware of the allegations at the time, Sanders said "no".
Politico's report said the "female staffer did not report the incident immediately because the campaign had just ended at the time of the incident". She reported the harassment after he contacted her again for a possible 2020 campaign.
"I intend in every way to be actively involved in that process", Sanders said.
Becker, now 50, told the woman he'd always wanted to have sex with her, she and three other witnesses told Politico.
Sanders was forced to respond to accusations reported by Politico that his campaign floor manager had forcibly kissed a 20-year-old campaign worker after making sexual suggestions to her.
Sanders, 77, is an independent who ran for the Democratic nomination in 2016.
"Candidates who allow people like Robert Becker to lead their organizations shouldn't earn the highest office in our government", the woman said.
The Vermont senator's campaign committee, Friends of Bernie Sanders, said Becker "would not be a part of any future campaigns".
The campaign of the 2016 presidential election in the United States was marred by episodes of sexual misconduct, especially by the then Republican candidate Donald Trump who eventually won the poll to become the president.
More than two dozen former staffers recently sent a letter to Sanders and his aides, seeking a meeting regarding the "sexual violence and harassment on the 2016 campaign" ahead of another bid for the presidency. Rather, Weaver told CNN, he'd serve as "a strategic adviser that needs to deal with some of the 30,000-foot issues as opposed to the management of a day-to-day campaign".
The reports of harassment are raising questions about whether Sanders can launch a second presidential campaign.