LAS VEGAS — A new ad criticizes Nevada Democratic Senate candidate Catherine Cortez Masto for being unaware of thousands of untested rape evidence kits.

The commercial announced Tuesday is from the Senate Leadership Fund, a super PAC aligned with Republican Senate Majority Leader Mitch McConnell that’s putting $6 million into the Nevada Senate race.

The spot features Cortez Masto testifying in 2014 while she was Nevada’s attorney general. She said she wasn’t aware that sexual assault evidence wasn’t processed.

The ad says she’s letting alleged rapists walk free.

Her campaign says local law enforcement agencies were responsible for the kits, and says her Republican opponent, Rep. Joe Heck, has repeatedly voted against funding to help rape victims.

Heck’s campaign says the votes were procedural motions and his real votes raised funding for victims.