Sen. Kirsten Gillibrand, D-N.Y., arrives for a news conference in Washington, D.C., on Nov. 19. Gillibrand is receiving plaudits for her efforts to change the way the military deals with rape. (J. Scott Applewhite/AP)

CLARIFICATION: This story was updated to accurately reflect Sen. Claire McCaskill’s opposition to the Gillibrand amendment. The senator’s office says she is concerned that the amendment does not do enough to protect victims against retaliation and about its overall effectiveness in bringing sexual assault cases to prosecution.

Sen. Kirsten Gillibrand (D-N.Y.) stood on the Senate floor for hours Wednesday dominating a debate over how the Pentagon should manage sexual assault and rape in the ranks.

Her main sparring partner was Sen. Claire McCaskill (D-Mo.), who is also pushing Congress to enact a significant change to military personnel policy. But Gillibrand is pushing for a more radical solution that would strip military commanders of any involvement in determining how rape and sexual assault cases are handled.

What becomes of the senators’ proposals and the defense authorization bill probably won’t be decided until Congress returns in mid-December from a two-week Thanksgiving break.

Even if Gillibrand comes up short on policy, she appears to have come out ahead politically. She has earned considerable goodwill from colleagues for methodically assembling a bipartisan coalition of support. On Wednesday, Gillibrand co-authored an op-ed on her proposal with Sen. Ted Cruz (R-Tex.). The day before, she stood with Republicans and Democrats at a news conference intended to build support, and Senate Majority Leader Harry M. Reid (D-Nev.) announced plans to back her.

During an interview in her office this week, Gillibrand kicked off her high heels, tucked her legs under her on a couch and declared: “I know I can make a difference here. I know that I can find common ground with any senator in that chamber — any senator in that chamber — and I will look for those solutions.”

There is near-universal agreement among lawmakers that the Pentagon must find a way to curb incidents of sexual assault and rape. The military estimates that as many as 26,000 service members were the targets of unwanted sexual contact last year, but only 3,374 incidents of sexual assault were reported to military officials.

In response, senators drafted this year’s defense bill to include the most significant rewrite of the Uniform Code of Military Justice in five decades — some say ever. If passed as written, the legislation would end the statute of limitations on cases of sexual assault or rape; strip military commanders of the ability to overturn jury convictions in sexual assault and rape cases; require that civilians review commanders’ decisions not to prosecute certain cases; make it a crime to retaliate against victims who report sexual assaults; and require the dishonorable discharge or dismissal of anyone convicted of sexual assault.

But Gillibrand and her coalition want to go further by stripping military commanders of any involvement in cases of sexual assault or rape and turning them over to specialized military prosecutors. She has spent months meeting with nearly every other senator to lobby for their support.

On Wednesday, Sen. Charles E. Grassley (R-Iowa), who is co-sponsoring Gillibrand’s amendment, called her passion “inspiring.”

Dimissing suggestions that her advocacy is about bolstering her standing in the Senate or her political bona fides, Gillibrand said: “This really isn’t about winning or losing. This is entirely about justice for victims of sexual assault and rape.”

Nevertheless, Gillibrand is still short of the 60 votes needed to ensure her amendment can clear procedural hurdles. Critics say the changes could radically alter a commander’s responsibility for good order and discipline among troops in the field and would add millions of dollars to the defense budget.

Gillibrand dismissed the criticism. “If the military is saying they can’t afford to prevent and to prosecute rapes, that’s an outrageous statement,” she said.

The public appears to agree with Gillibrand. A Washington Post-ABC News poll released this week found that nearly six in 10 Americans believe that decisions on whether to prosecute allegations of sexual assault in the U.S. military should be made by an independent group of military prosecutors instead of within the military chain of command.

McCaskill, a former state prosecutor, maintains that the Gillibrand proposal goes too far. She said her review of military records found no example of a commander declining to refer a serious case for prosecution. But there are almost 100 cases in the past two years in which prosecutors declined to take a sexual assault case and a commander insisted that it be tried, she said.

“If you want more prosecutions and if you want to hold the commanders accountable, I think it’s a dramatic mistake to let the commanders walk away,” McCaskill said in an interview. “I think it’s a dramatic mistake to say that a lawyer half a continent away is going to make the call and that somehow is going to protect this victim more from retaliation and result in more cases getting to court.”

McCaskill is pushing instead to drop the “good soldier” defense from military evidence rules in sexual assault and rape cases unless a defendant’s military character is directly relevant to the crime alleged. She also wants more stringent civilian review of disagreements between military prosecutors and commanders. Her proposals are expected to easily pass the Senate.

Gillibrand said she is “grateful” for McCaskill’s work on the issue and for ensuring that several significant changes will occur this year. She said the disagreement “confirms what I know about what women bring to the table,” Gillibrand said, “that this common sensibility, this eagerness to get things done, this desire to find consensus and build broad consensus to get things done is real.”

She seemed undeterred by the possibility that her proposal will fail to garner sufficient support. If that happens, “I will work on this as long as I’m in the U.S. Senate,” she said. “I think it’s something that will always need advocacy.”

Polling analysts Scott Clement and Peyton M. Craighill contributed to this report.