* Gillibrand sees 51 votes for bill
* Conservatives back shift away from chain of command
By Patricia Zengerle
WASHINGTON, July 16 (Reuters) - Two Senate Republicans on Tuesday backed a sweeping change to how the military handles cases of sexual assault, boosting a plan that faces strong opposition at the Pentagon and in Congress.
U.S. Senators Ted Cruz and Rand Paul said they supported Democrat Kirsten Gillibrand's proposal to take the decision about whether to pursue sexual assault cases away from a victim's commander and place it with independent military prosecutors.
Debate over the military's sexual assault problem has been intense since a spate of high-profile cases and a Pentagon study in May showing incidences of unwanted sexual contact, from groping to rape, were up 37 percent in 2012 from 2011.
Gillibrand's plan is opposed by most Republicans and some Democrats, including Carl Levin, the chairman of the Senate Armed Services Committee. Pentagon leaders say they fear it would weaken the chain of command.
Paul and Cruz, favorites of the conservative Tea Party movement, said they were concerned by how few military victims reported sexual assaults.
"I see no reason why conservatives shouldn't support this. The only thing I think standing in the way is just sort of the status quo," Paul said at a news conference.
"If it appears as if there is some deterrence to victims reporting the crime, why don't we fix it?" he asked.
Cruz noted that U.S. allies including Britain, Australia and Israel have already shifted the decision on sexual assault cases from commanders without lessening military discipline or readiness.
Gillibrand said the backing of Paul and Cruz means that at least 41 senators support her plan, which has 33 co-sponsors in the Senate, including other Republicans such as Chuck Grassley. "We will get to 51," she told Reuters, referring to the majority in the 100-member Senate.
Gillibrand promised a fight in the full Senate after the Armed Services panel rejected the plan last month. The panel opted instead for Levin's proposal to let military commanders continue deciding whether to bring sexual assault cases to trial, but add levels of review by more senior leaders.
That plan did not go far enough, Gillibrand said, because only 300 cases out of the 26,000 each year go to trial, largely because victims do not trust commanders.
"Not every commander is going to understand that rape is a serious, violent crime of domination, often not even related to gaining a romance, more often related to dominance and violence and power," she said.
A probe by the Pentagon's inspector general released on Monday found that the military in many cases does not properly investigate allegations of sexual assault.
Levin still opposes Gillibrand's plan.
"If you remove the chain of command, you are taking away from the chain of command the club that they need to change the culture, which is the club of being able to prosecute someone," he said at a breakfast sponsored by the Christian Science Monitor. (Editing by Doina Chiacu)