Sen. Kirsten Gillibrand’s quest for military justice reform faced another setback on Tuesday, when the Senate blocked a vote to include the Military Justice Improvement Act (MJIA) as an amendment to the 2016 National Defense Authorization Act (NDAA).

The amendment failed on a 50-49 vote; it had majority support, but did not get the 60 votes required to overcome a filibuster. Last year, the MJIA fell five votes short of overcoming a filibuster.

The MJIA would end the practice of letting military commanders make decisions about prosecuting sexual assault cases from their ranks.

Gillibrand, along with many advocates for military sexual assault survivors, says these reforms are necessary because survivors don’t trust the system. Commanders often retaliate against survivors, or they may even be the ones accused of assault. Even sympathetic commanders are said to lack the legal training they would need to properly assess the cases.

A recent report from Human Rights Watch found reports of retaliation against service members who report sexual assault. Survivors most often report being socially ostracized and threatened with violence by their peers, but they say commanders also retaliate by refusing to promote victims or demoting them to lesser duties.

The Pentagon’s most recent survey on sexual assault found that rates of retaliation haven’t changed, and that one in seven survivors was assaulted by someone in their chain of command.

“It is unacceptable that the retaliation rate has remained unchanged, and that the Pentagon cannot point to a single case where a penalty was levied against an individual who retaliated against a survivor who reported,” Gillibrand said in a statement after the vote.

The MJIA has an unlikely list of bipartisan supporters, including Sens. Ted Cruz (R-TX) and Rand Paul (R-KY). A prominent Democratic opponent of the bill is Sen. Claire McCaskill (R-MO), who says that the reform wouldn’t do anything to prevent retaliation.

Gillibrand has called on President Obama to publicly support the bill, arguing that military brass—and thus the members of Congress who follow the Pentagon’s lead—would change their position “overnight” if the commander-in-chief declared the reform necessary.

“Those opposed to a fair justice system for our troops and their families are listening to the same generals that were against gay Americans serving their country or allowing women to serve equally,” said retired Colonel Don Christensen, the Air Force’s former chief prosecutor, in a statement.