Fifty members of the Senate are now publicly backing a proposal by New York Sen. Kirsten Gillibrand to let military prosecutors rather than commanders decide whether to prosecute sexual assaults in the military.

Nevada’s senators announced their support on Tuesday, reducing the number of publicly undecided members of the Senate to about 25. The separate announcements by Republican Sen. Dean Heller and Democratic Majority Leader Harry Reid came as Gillibrand, a Democrat, continued meeting privately with undecided senators.

Heller said he decided there needed to be three standards — that victims “must feel confident’’ they can report a crime, that they are “protected from sexual harassment’’ and victims “should feel confident that justice will be served.”

“That’s what brings me to the table today,” said Heller, who joined Gillibrand at a news conference. “This amendment does do that. What it does is tell the commander in the field, ‘You can go back to doing your job and get the troops ready.’ ”

Gillibrand plans to offer her proposal as an amendment to a defense authorization measure the Senate is debating this week.