Senator Bernie Sanders, accelerating his efforts to contain the damage from reports of sexism and harassment during his 2016 presidential campaign, plans to meet on Wednesday with a group of former staff members seeking assurances of better practices if he runs again in 2020.

As other potential presidential candidates prepare to roll out campaigns with forceful, positive messaging, Mr. Sanders and his supporters have instead been forced to play defense, addressing allegations during his last presidential bid.

The meeting on Wednesday, which will be held in Washington, will focus on the treatment of women going forward, some invitees and people close to Mr. Sanders said Monday. Mr. Sanders’s campaign arm began reaching out to the former staff members to help make travel arrangements and intends to pay for air travel and hotel expenses, the people said.

Mr. Sanders plans to attend a portion of the meeting.

The steps Mr. Sanders and his supporters have taken over the last week underscore the sense of urgency the senator faces as he prepares for a likely 2020 campaign. Though he has not yet announced that he intends to run, he has told aides and advisers that a decision is coming soon.