Members of Congress said they are so angry about the crescendo of sex-crime scandals in the armed forces that they are considering fundamental changes to military law and other measures that the Pentagon has resisted for years.

Lawmakers from both parties said Wednesday that they were appalled by the latest revelation: that the Army is investigating a sexual-assault prevention officer on suspicion of sex abuse and pimping. Several members pledged to overhaul the way the military punishes offenders and protects victims of sexual assault.

“There’s a shift in the debate, that we need real reform and accountability,” said Sen. Kirsten Gillibrand (D-N.Y.), a member of the Senate Armed Services Committee. “The recent cases have demonstrated just how severe the problem is.”

Gillibrand said she will introduce a bill Thursday that would rewrite military law by removing the authority of commanders to decide whether to investigate and prosecute serious crimes, including sexual assault. The authority would be transferred to independent military prosecutors in what would be the biggest revision of the Uniform Code of Military Justice in three decades.

Military leaders have long opposed the shift, and until recently there appeared to be little appetite on Capitol Hill to force such a change on the Pentagon. But the mood has changed after disclosures of a sharp rise in sexual assaults and individual scandals. Many lawmakers said they have lost faith in the military’s ability to tackle the problem of sexual assault.

“The harsh reality is our military is failing,” said Rep. Susan A. Davis (D-Calif.), a member of the House Armed Services Committee. “Americans don’t accept failure, and I worry that we are approaching a crisis point.”

Army officials acknowledged that they had opened a criminal investigation into allegations that an unidentified sexual-
assault prevention officer at Fort Hood, Tex., had sexually abused women, including a subordinate whom he allegedly forced into prostitution.

That disclosure follows the arrest last week of an Air Force sexual-assault prevention officer on charges of sexual battery. Police said the officer drunkenly groped a stranger in a Northern Virginia parking lot.

The incidents prompted several lawmakers on Wednesday to introduce bills that would establish stricter criteria for sexual-
assault prevention programs in the military. Defense Secretary Chuck Hagel has ordered the retraining and rescreening of 9,000 personnel who serve as sexual-
assault prevention officers.

The Defense Department is struggling to cope with what its leaders describe as an epidemic of sex crimes, most of which go unreported and unprosecuted. Last week, defense officials released a report estimating that the number of military personnel victimized by “unwanted sexual contact” had surged by about 35 percent in the past two years, despite intensive efforts to confront the problem.

As a result, the Pentagon’s resistance to legislative interventions has faded.

On May 7, Hagel indicated to reporters that he would oppose a bill like Gillibrand’s that would remove commanders’ authority to oversee sexual-assault investigations and prosecutions. “It is my strong belief,” he said, “the ultimate authority has to remain within the command structure.”

A few days alter, however, Hagel retreated. On Monday, a Pentagon spokesman told reporters that the defense secretary was “open to any and all options.”

In an interview, Gillibrand said she recently had a frank conversation with Hagel to press her proposal. “He was open-minded and he listened,” she said.

The Pentagon has already capitulated to another legislative proposal that would curtail commanders’ authority to grant clemency to convicted sex offenders. In March, several military leaders testified before Congress that such decisions were exceedingly rare and that it would be a mistake to tinker with military law.

A few weeks later, however, Hagel announced that the Pentagon had reversed course and would support the measure “They changed their view 100 percent,” Gillibrand noted.

Some influential lawmakers remain unconvinced that further changes are necessary.

Sen. John McCain (R-Ariz.), also a member of the Armed Services Committee, said he was “appalled” by recent disclosures of sexual misconduct in the military. But he expressed reservations about restricting commanders’ powers.

“Whatever we do, we need to make sure that we preserve the command structure in the military,” he said. “We may need to make changes to it, but our military’s been functioning for well over 200 years. . . . We need to have more hearings, we need to examine it, but for us to rush to judgment and pass legislation without hearings I think is inappropriate.”

Similarly, Rep. Howard P. “Buck” McKeon (R-Calif.), chairman of the House Armed Services Committee, has indicated that he favors management and policy changes over legislative ones. On Wednesday, he spoke with Hagel by phone and urged him to “shake up the change of command” by holding military leaders responsible for sexual assault in the ranks, aides said.

Eugene R. Fidell, a military-law expert at Yale Law School, said shifting responsibility for prosecuting serious crimes outside the usual chain of command makes sense. Britain, Canada, New Zealand, Ireland and Israel adopted similar changes years ago, he said.

“Some perfectly estimable democracies that speak our language and share our values have done this without the sky falling,” he said.

Fidell said it has been 30 years since Congress made substantial changes to the Uniform Code of Military Justice. Concerns about the handling of sex crimes could prompt another major reform.

“It’s clearly one of those pivotal moments,” he said. “And they occur in our country in response to critical episodes, or a collection of episodes like the ones we’re seeing now.”

Ed O’Keefe contributed to this report.