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 4’s Today programme that the introduction of the complaints scheme had been “a big step in the right direction towards ensuring everyone’s treated with dignity and respect”.
She said the “clear advice” at the time was that it would be “very difficult to bring in historical complaints and it might risk the integrity of the scheme due to the possibility of legal challenge”.
But she said there has been “an element of change” in MPs’ views now the scheme was up and running and “working well” and said she did believe that people should be able to bring forward historical allegations.
“I do think that there is a real desire in Parliament to see proper change,” she said.
When asked whether the Commons Speaker John Bercow, who has faced claims of bullying, should be investigated, Mrs Leadsom said: “I’ve always refused to make this specific to one individual.”
But she said an individual “will be held to account” if there was “a finding against an individual”.
Mr Bercow has denied the allegations.
Mrs Leadsom added: “I’m delighted that now people with historical complaints will be able to come forward and the case will be investigated strictly confidentially.”
Focus on MPs’ staff
Last week a report by senior lawyer Gemma White, which focused on how MPs treated their employees, said the most common form of offending behaviour was shouting at, demeaning, belittling and humiliating staff, often in public.
It also said sexual harassment was also a problem, with staff being subject to unwanted advances – often accompanied by touching and sometimes forceful.
However, many MPs had also been described as “excellent employers, colleagues and managers”.
This report came a day after another inquiry found that staff were “bullied and harassed” by “known offenders” in the House of Lords.
MPs will debate the Gemma White report in the Commons on Wednesday afternoon, and then consider and vote on the government motion, with a result expected from about 19:00 BST.