TRENTON, N.J.—The famously liberal Bruce Springsteen has never said anything publicly about one of his biggest fans, New Jersey's Republican Gov. Chris Christie.

But the Boss' 20-year-old daughter is addressing Christie.

The American Society for the Prevention of Cruelty to Animals says accomplished equestrian Jessica Springsteen has signed a letter urging Christie to sign a bill that would ban slaughtering horses in the state.

New Jersey's Legislature passed the bill in June.

There's no word on what the governor intends to do with the bill.