Democratic U.S. Sen. Amy Klobuchar has signed on to a letter asking NFL Commissioner Roger Goodell to adopt a "real zero-tolerance policy for domestic violence."

Klobuchar is among sixteen women U.S. senators criticizing the league's handling of the domestic abuse case of player Ray Rice after the recent release of video by TMZ.com showing him striking his now-wife, knocking her unconscious.

"We were shocked and disgusted by the images we saw this week of one of your players violently assaulting his now-wife," the senators wrote. "Tragically, this is not the only case of an NFL player allegedly assaulting a woman even within the last year."

The Baltimore Ravens terminated Rice's contract and the NFL suspended him indefinitely following the release of the footage.

Goodell initially suspended Rice for two games. Facing mounting criticism for the decision, the NFL established a six-game unpaid suspension for players who violate the league's policy on domestic violence and a lifetime ban for a second offense.

"We are deeply concerned that the NFL's new policy, announced last month, would allow a player to commit a violent act against a woman and return after a short suspension," the senators wrote. "The NFL's current policy sends a terrible message to players, fans and all Americans that even after committing a terrible act of violence, you can quickly be back on the field."

Goodell Letter