MPs are due to vote on allowing the parliamentary complaints scheme to investigate historical allegations.
The government motion would allow those from before June 2017 to be considered.
It comes after a report last week said there was a “significant problem” of MPs bullying and harassing staff, including some who were making unwanted sexual advances.
Ex-Commons Leader Andrea Leadsom said there was “a real desire in Parliament to see proper change”.
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.
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Mrs Leadsom told BBC Radio 4’s Today programme the introduction of the complaints scheme had been “a big step… 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.
When asked whether 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.”
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, often in public.
It also said sexual harassment was a problem, with staff being subjected to unwanted advances – often accompanied by touching and sometimes forceful.
However, many MPs had also been described as “excellent employers, colleagues and managers”.
Eliot Wilson, a former parliamentary staff member who was a clerk for 11 years, told BBC’s Victoria Derbyshire there was a “culture of saying ‘well, you just get on with it'” and this was “very, very corrosive”.
“I think there is still a culture where you have to accept it, you get on with your job, you do your best, but you accommodate the fact that some members of Parliament are well known to be either bullies or unsafe to be in the company of young women alone.”
Hannah White, who worked as a clerk in the House of Commons for 10 years, said she had “experienced instances of bullying behaviour by senior MPs”, including being berated in a remote corridor “for simply having done my job”.
She said she would be able to make a complaint if the Commons votes in favour of allowing historical incidents to be investigated, but it was difficult for those who were still pursuing a career in the House as they were in a “uniquely vulnerable position”.
She added that it was “notable” since the White report “how few current staff have been willing to speak out”.
The 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 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.
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