Congressional measures targeting sexual assault in the military gained momentum Thursday as lawmakers voiced growing support for overhauling how decisions about prosecuting sex crimes are made.

Proposals in both chambers would strip military commanders of the authority to decide which alleged incidents of sexual assault are tried in military courts and which result in lesser punishments or are dismissed, reflecting lawmakers’ frustration with the failure of earlier attempts to end the scourge of harassment and assault in the ranks.

The measures, championed by Rep. Jackie Speier (D-Calif.) in the House and Sen. Kirsten Gillibrand (D-N.Y.) in the Senate, are gaining support despite opposition from military leaders, who for years have argued that commanders must retain responsibility for their subordinates’ actions to effectively lead units and prepare them for battle.

Speier, joined by House Speaker Nancy Pelosi (D-Calif.) and the family of slain soldier Vanessa Guillén at a news conference outside the Capitol, said previous initiatives had fallen short. Under her proposal, independent military prosecutors, rather than commanders, would decide which cases are tried, reducing the potential for conflicts of interest.

“A strong bipartisan coalition of members has made it clear: The clock has run out on the Department of Defense half-measures,” Speier said. “Major transformational change is needed, not only in the military justice system but also in the culture and command climate in the military.” Speier’s office later said the measure had more than 170 co-sponsors.

Speier’s bill is named for Guillén, a young Army specialist whose murder by a fellow soldier at Fort Hood in April 2020 triggered a reckoning over how the Army responds to soldier harassment and disappearances.

After Guillén’s death, investigators found that a “toxic culture” at the Texas base allowed sexual harassment to flourish. They also identified systemic problems with military discipline and initiatives designed to keep soldiers safe.

Before her disappearance, Guillén confided in others about being sexually harassed but, like many other troops, did not make an official complaint to her superiors.

The statements came hours after Gillibrand’s office announced that a related bill, the Military Justice Improvement Act, had secured the support of a bipartisan group of 61 co-sponsors. The bill’s attainment of that threshold, probably representing even wider support and meaning the measure cannot be filibustered, was first reported by the Wall Street Journal.

Lawmakers in both chambers may attempt to pass the measures as part of an annual defense bill.

Also Thursday, the Pentagon released annual figures showing a slight increase in sexual assaults reported during military service. The number of reported incidents increased from 6,236 in fiscal 2019 to 6,290 in fiscal 2020.

The data showed that only a small share of the reported incidents — 156 cases — resulted in a conviction at a military trial.

Pentagon spokesman John Kirby said the report’s findings underscored that more needed to be done regarding sexual assault. “We will stay at this important work, and we will be unafraid to find creative solutions,” he said in a statement.

Because of the coronavirus pandemic, a biennial survey on sexual harassment and assault that was supposed to take place in 2020 was postponed.

Defense Secretary Lloyd Austin, a retired four-star general, has vowed stronger action against sexual assault, which officials say can compound the military’s recruitment and retention challenges. Female service members tend to leave the military earlier than men do, often citing the toll of harassment or assault.

A panel appointed by Austin to review the problem has endorsed the proposed shift in the way prosecution decisions are made. The current military chiefs, including Gen. Mark Milley, chairman of the Joint Chiefs of Staff, have all voiced opposition to it. But Milley recently said commanders had lost the trust of troops and signaled that he is open to the change.

Speier’s bill would also create a provision under the Uniform Code of Military Justice prohibiting sexual harassment and would permit troops for the first time to seek monetary damages for sexual harassment or assault by other Defense Department personnel.

Gillibrand’s proposal, meanwhile, would also give independent military lawyers decision-making power over other serious crimes.

Speaking as Speier reintroduced her bill, Rep. Adam Smith (D-Wash.), chairman of the House Armed Services Committee, said the problems were larger even than the numerous ones found at Fort Hood. “No one piece of legislation is going to change this, but the legislation Jackie has put forward is our best shot,” he said. “The culture within the military must fundamentally change.”

Pelosi, who called sexual assault an “epidemic,” said that “we will not stop until we pass this bill.”

In an email, Natalie Khawam, a lawyer who represents the Guillén family, said the changes could reverse the morale problems created by the prevalence of harassment and assault.

“We will never be able to bring Spec. Vanessa Guillén back to us, which is a great loss to our country, but with this bill, Vanessa did not die in vain,” she said.

Alex Horton contributed to this report.