BOSTON — The reluctance of harassment victims to come forward with complaints against the state Legislature demonstrates the need for an independent commission that could investigate any allegations, a senator said on Friday.

Sen. Jamie Eldridge, a Democrat from Acton, said he plans to file legislation establishing the permanent, nine-member commission in the coming days.

“There is a fear that if someone complains, they will be marginalized or retaliated against,” Eldridge said.

While both legislative chambers have written policies for handling harassment complaints, people who have been victimized often must go through House or Senate counsel with close ties to legislative leadership, he said.

The Senate Ethics Committee has retained a Boston law firm to investigate whether Sen. Stan Rosenberg violated any Senate rules after The Boston Globe reported on allegations that his husband, Bryon Hefner, sexually abused several men, including some who had dealings with the Legislature.

Rosenberg, an Amherst Democrat, has maintained his husband had no influence over his policy decisions or actions by the Senate. He has stepped aside as Senate president for the duration of the investigation. He has not been accused of wrongdoing and has said his husband is seeking professional help.

Democratic House Speaker Robert DeLeo recently ordered a review of House rules and procedures related to sexual harassment complaints.

According to a draft summary of Eldridge’s proposal, the commission would consist of five members appointed by the governor, the attorney general and the state auditor and four members appointed by the Legislature. The commission would be required to include at least one sexual assault counselor, one licensed social worker with experience in sexual harassment outreach and one human resources professional with experience in workplace harassment training.

The commission could review any allegations made by or against lawmakers, legislative staff or interns or any person “whose essential job functions are substantially related to the operation” of the Legislature, a definition that could encompass lobbyists and policy advocates.

While the commission would not, under the proposal, have the authority to impose discipline, it could send any findings to law enforcement officials and to the House or Senate ethics committees.

The commission would first establish guidelines for protecting the confidentiality of people who come forward with complaints and of witnesses.

“I think the culture has improved, the workplace environment has improved,” said Eldridge, a legislator for 15 years. “But I still think there are institutional problems,” including the fear that a person’s professional life would suffer should he or she go public or raise an issue about the Legislature.