SACRAMENTO — Republicans took a rare victory lap in the Senate chambers Thursday after lawmakers unanimously approved whistle-blower protections for legislative employees, many of whom have come forward in recent months to say they fear reporting sexual harassment and abuse because of retaliation.

One by one, Republicans laid blame squarely on the Senate Democratic leaders who have quietly killed whistle-blower protections four times since 2014 before abruptly reviving the legislation, AB403, by Assemblywoman Melissa Melendez, R-Lake Elsinore (Riverside County).

“Sadly, this bill has taken four years,” said Sen. Joel Anderson, R-Alpine (San Diego County). “I don’t know why leadership wouldn’t want it.”

Sen. Jeff Stone, R-Temecula (Riverside County), said it was a “travesty of partisanship” that the bill was hung up for years and credited Melendez’s efforts “over the past four years to try to get the institution to do the right thing.”

“This should be a lesson to us,” he said, “that when the other side comes up with a good idea that enhances public safety and enhances us doing the right thing, that we shouldn’t let partisan divides get in the way of doing something that’s right.”

The bill now heads to the state Assembly, which could vote on it as early as Monday.

The about-face by Democratic leaders to support the bill came as the #MeToo movement spotlighted sexual improprieties at the Capitol. Women have accused three Democrats of misconduct, leading to two resignations and one suspension and to pressure on the Senate leadership to explain why they’d sat on the whistle-blower legislation for years.

Sen. Ricardo Lara, D-Bell Gardens (Los Angeles County), and Senate President Pro Tem Kevin de León, D-Los Angeles, made the decision to hold the bill in the Senate Appropriations Committee, which Lara chairs. Previously, neither would comment on why the bills were killed in 2014, 2015 and 2016. Melendez last year reintroduced a new version of the bill, which was also shelved in the Senate committee in June. De León released the bill last month and sent it to the Senate floor for a vote.

Melendez said she was not given any explanation, so she continued to author the bills each year.

On Thursday, de León finally offered an explanation for why the Melendez bills died in the Senate committee: He said he felt there were sufficient protections under Senate anti-retaliation and sexual harassment policies.

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“We have our Senate rules that cover it,” de León said Thursday. “In the wake of the #MeToo movement, I think it was appropriate to release the measure and make the bill a better bill, because we added the sexual harassment component.”

Melendez bristled at de Leon’s suggestion that her previous measures would not have helped sexual harassment victims. Melendez’s bills previously said legislative employees were protected for any allegation involving a standard-of-conduct complaint.

“Sexual harassment has always been in the bill; it just hasn’t been the only thing in the bill,” Melendez said.

The bill’s 38-0 passage comes as the Senate and Assembly prepare to release a cache of documents that were previously withheld from the public by each house. In December, leadership in both houses reversed course and said they would release substantiated sexual harassment claims against lawmakers and high-level employees where “discipline has been imposed or allegations have been determined to be well-founded.”

Those documents could be released as early as Friday. Both the Senate and Assembly have been dealing with accusations against lawmakers, with Assemblymen Raul Bocanegra, D-San Fernando Valley (Los Angeles County), and Matt Dababneh, D-Encino (Los Angeles County), resigning late last year, while Sen. Tony Mendoza, D-Artesia (Los Angeles County), remains suspended pending an investigation into sexual misconduct allegations. All three have denied wrongdoing.

AB403 says, “Legislative employees should be free to report legal and ethical violations without fear of retribution.” Employees of lawmakers have never been covered under the California Whistleblower Protection Act, which was expanded over the years to include additional workplaces like the governor’s office and legislative-appointed positions.

Under the bill, anyone who intentionally retaliates against a whistle-blower in the Legislature could be fined up to $10,000 and jailed for up to a year, and could be sued by the whistle-blower in civil court. The protections in the bill would also cover volunteers, interns, fellows and those applying for a job in the Legislature.

Melendez added an urgency clause to the bill that would allow it to take effect immediately if it passes the Assembly and is signed by Brown. That would ensure that the protections cover whistle-blowers as soon as possible, Melendez said.

“Once they have this protection in place, I think they can breathe a little bit of a sigh of relief and say, ‘Now I can come forward,’” Melendez said.

More than half of the 120 lawmakers in the Legislature signed onto the bill as co-authors before the Senate vote. And while no one voted against the bill Thursday, one senator abstained.

Sen. Holly Mitchell, D-Los Angeles, abstained from voting, saying she supports the concept of the bill, but that a joint committee she is on is working on broader reforms to address sexual harassment and abuse. Mitchell left the Senate chambers before the vote took place.

“I’ve heard a lot of talk today about creating a safe space in which people can report,” Mitchell said. “I hope everyone who spoke today will give the same amount of energy and credence and effort around creating a culture that prevents circumstances that require reporting.”

On Tuesday, the Senate approved SB419 by Sen. Anthony Portantino, D-La Cañada Flintridge (Los Angeles County), another whistle-blower protection bill that includes legislative employees and lobbyists and requires both the Senate and Assembly to retain harassment and discrimination complaints for 12 years. Portantino had previously tried to pass whistle-blower protections for legislative employees in 2011 and 2012. Both times, the bills failed in an Assembly committee.

On Tuesday, AB419 passed with a unanimous 39-0 vote, including Mitchell’s.

“There has been a clear lack of transparency, accountability and trust in how the Legislature handles issues of sexual harassment,” said Sen. Connie Leyva, D-Chino (San Bernardino County). “Retaliation is one of the biggest barriers for women and men who want to file a complaint about sexual harassment. The Legislature must lead by example.”

Melody Gutierrez is a San Francisco Chronicle staff writer. Email: mgutierrez@sfchronicle.com Twitter: @MelodyGutierrez