The comment was accidentally recorded on voice mail after Brown thought he hung up the phone after leaving a message for the Los Angeles Police Union.
Fox News says people with knowledge of what happened say it was Brown's wife who suggested calling Whitman a "whore," for cutting a deal to get the union's endorsement.
Brown's campaign did not respond to ABC7's e-mails on Sunday and they still haven't said who said it.
Whitman is demanding a personal apology.
The Fox News source notes that Brown's wife, Anne, is a former executive at The Gap and can't exactly be fired from the campaign.