The top Republican on the Senate Armed Services Committee is telling his GOP colleagues to get in line with Sen. Claire McCaskill's approach on military sexual assault.

The demand: Don't be so quick to support an alternative offered by Sen. Kirsten Gillibrand, D-N.Y.

"I have done the research, and I invite you to do the same," Sen. Jim Inhofe, R-Okla., writes in a blunt letter to Republican senators Friday. "When you do, I expect you will discover that removing authority from commanders would be a grave mistake."

Inhofe’s message seeks to clear up “misconceptions” that other senators might have about the two approaches. McCaskill made a similar plea Thursday, when she some senators might be “confused” about what the Gillibrand approach does. 

McCaskill, D-Mo., proposes allowing military commanders to retain the power to decide whether to prosecute military sexual assault cases, while forcing higher-ranking officials to review any case they choose not to prosecute.

Gillibrand favors removing the chain of command from this decision and giving this authority instead to independent prosecutors.

The Armed Services Committee voted to adopt McCaskill's proposal over Gilibrand's.

Inhofe argues in the letter that victims of sexual assault don't refuse to report the assaults because they fear retaliation within the military but because they don't want the incident to become public. Taking the authority to decide those cases out of the hands of the chain of command, he said, would reduce the commander's ability to address the problem of sexual violence within the military. Moreover, victims already have options to report their sexual assaults outside of the chain of command, he said.

Inhofe's letter comes just as momentum is building behind Gillibrand's alternative approach.

Gillibrand's office said her alternative is backed by 44 senators and gained two new co-sponsors on Wednesday. She needs 51 senators to support her amendment when the Defense Authorization Act comes to the Senate floor this fall and she's been aggressively lobbying fellow senators to back the measure.

McCaskill, on the other hand, is playing defense. Her proposal has already been adopted by the Senate Armed Services Committee on a 17-9 vote. With no new legislation to push, her effort is less aggressive than Gillibrand's.

"We're just trying to meet at either the member or staff level with offices that have questions or concerns," a McCaskill aide said.