WASHINGTON (CNN) -- An effort to remove sexual assault cases from the military chain of command received a bipartisan boost Tuesday as conservative Republicans joined the bill's main backer, Democratic Sen. Kirsten Gillibrand, to voice their support for the measure.
"Our carefully crafted common sense proposal was written in direct response to what the victims told us, the stories that came from them, what happened to them, the fact that they didn't trust the chain of command, that they were retaliated against, that they didn't think justice was possible," Gillibrand said at a Capitol Hill event.
The proposed law comes after a spike in sexual assault cases in the armed forces, which has prompted President Barack Obama and top military brass to vow change. A report Monday from a government watchdog found that in many cases the military did not properly investigate sexual assault claims.
The bill is an extension of Gillibrand's efforts in the Senate Armed Services Committee to advance legislation requiring decisions about sexual assault cases to be made by independent military prosecutors. The measure faced opposition from senior military leaders, who argued it would harm commanders' ability to lead effectively.
It also met resistance from the Armed Services Committee's Democratic Chairman, Sen. Carl Levin, who replaced Gillibrand's provision with a measure that would require review of prosecution decisions by more senior military leaders. Levin's proposal would also make it a crime to retaliate against those who report an assault.
Gillibrand argued that one of the problems with Levin's measure is that continues to place the responsibility for prosecuting sexual assaults in the hands of commanders, even though military prosecutors have the proper training in handling these cases and determining which should go to trial.
"Not all commanders will have the determination that we saw the military brass pledge in the last hearing," she said. "Not every commander is going to understand that rape is a serious, violent crime of domination, often not even related to dating or romance; more often related to dominance and violence and power."
After Gillibrand's measure stalled in committee, the New York Democrat has been working to gain support for the measure in the full Senate. If she garners 51 co-sponsors for the provision, it would force a debate in the upper chamber.
Two prominent tea party-backed senators, Republicans Ted Cruz and Rand Paul, have thrown their weight behind the measure. They joined conservative Republican Sen. Charles Grassley of Iowa and liberal Democratic Sen. Barbara Boxer of California in publicly backing Gillibrand's amendment.
"I see no reason why conservatives shouldn't support this. The only thing I see standing in the way is just sort of the status quo," Paul said Tuesday.
Cruz admitted he had been undecided when he entered the committee hearing last month, but was persuaded by Gillibrand to back the proposal. He mentioned the fact that one of the most persistent problems in prosecuting or deterring these crimes is the fact that the victims of sexual assault have remained reluctant to come forward and report the crimes.
He also pointed to the policies in place by allied militaries, including Great Britain, Israel, and Germany, that are similar to the one proposed by Gillibrand.
"I am a big believer in following the data where they lead. And the fact that other professional militaries had been able to maintain discipline, maintain the chain of command, maintain readiness, maintain effectiveness, and at the same time improve reporting and improve deterrence to me was persuasive," Cruz said.
The senators' efforts come amid mounting outrage over sexual abuse cases in the armed forces. Earlier this year, the Department of Defense released figures estimating 26,000 cases of unwanted sexual contact occurred in 2012, a 35% jump from 2010. Those cases ranged from groping to rape. The vast majority of those incidents went unreported as crimes, the study showed.
Grassley voiced concern that if Congress doesn't act on this increasing problem it could have lasting impact on the military's future.
"If we don't crack down on the individuals who use sexual violence as a means of personal power and personal gain then we'll create lingering institutional problems that will jeopardize moral and impact recruitment and retention of troops," he said
On Monday, a report from the Pentagon's inspector general found that most investigations of sexual assault allegations in the military in 2012 met requirements. However, 11% of those investigations -- or 56 cases last year - had serious problems, including evidence not being collected and witness interviews not being completed.
CNN's Bryan Koenig contributed to this report.
CNN's Bryan Koenig contributed to this report.