MPs are due to vote on allowing the parliamentary complaints scheme to investigate historical allegations.
The government motion would amend the independent complaints and grievance scheme to allow inquiries into claims before June 2017.
It comes after a report last week said there was a “significant problem” of MPs bullying and harassing staff.
Ex-Commons Leader Andrea Leadsom said she was “delighted” the motion will help those with older claims.
Allegations of bullying and harassment in Parliament first made headlines in 2017, and in October last year a damning report by High Court judge Dame Laura Cox found lewd, aggressive and intimidating behaviour by MPs and senior staff had been “tolerated and concealed” for years.
A new independent complaints scheme was then introduced in Parliament in 2018.
Mrs Leadsom told BBC Radio