Los Angeles (CNN) -- Shock jock Howard Stern's addition as a judge on NBC's "America's Got Talent" could cost advertisers "countless millions of dollars in customer goodwill," a parents group is warning.
"NBC's decision to add Mr. Stern to AGT will likely result in a sharp increase in explicit content, and we urge you to be mindful when considering a media buy," Tim Winter, president of the Parents Television Council, said in a letter to 91 companies that have previously bought time on the show.
Stern, whose show is heard on Sirius XM Radio, was hired to replace CNN host Piers Morgan as a judge for the seventh season of the highly rated talent competition. The show, which returns to TV on May 14, is mostly broadcast live.
NBC did not respond to multiples CNN requests for comment on the letter Monday morning.
Stern's publicist pointed CNN to an online video of interviews of three unidentified women who attended a recent show taping. All three women said before the taping that they expect to Stern to be crude. They each praised his performance afterward.
"He wasn't that crude today," one woman said. "He did make a 7-year-old cry; however, I think he did a great job and he was fair."
Another woman said she cried when Stern hugged that child to make him feel better.
When Winter's group issued a statement in December calling Stern's hiring "an act of desperation for a flailing network," Stern responded with a call to Morgan's CNN show.
"Networks shudder" at criticisms from such groups, Stern said. "They start to complain that I'm some sort of weird pervert who's going to convert Americans into zombie sex fiends, but I can assure you and the rest of America what I'm looking at here is to be a very good judge."
Stern said he will take his judging duties seriously with a goal "to actually find someone who can become a major superstar."
The head of the Parents Television Council, which has a mission of "protecting children against sex, violence and profanity in entertainment, was not persuaded.
Winter asked potential sponsors to consider whether Stern's "decades-long penchant for profanity, his affinity for degrading and sexualizing women, and his proclivity for vulgar and explicit dialog" accurately reflect their corporate values.
"Stern's reputation for sleaze and misogyny is well known; and to our knowledge his only previous judging experience consisted of looking at insecure, naked young women and telling them whether or not they were hot enough to pose for Playboy," Winter wrote said.
The letter quoted a radio broadcast in which Stern told a female guest: "I would like to kiss you and chop off your feet. ... I wanna bite off your fingers. ... I wanna have sex with you and throw you in a ditch ... (and) chop your head off."
"Does such commentary accurately reflect your corporate values?" Winter asked.
Advertisers must have a "presumption that Mr. Stern will only continue to conduct himself in precisely the same manner as he has done for decades," the letter said.
"Unless and until his conduct consistently reflects and respects the time, place and manner of an 8 p.m. broadcast television program, we would urge you and your advertising agency to consider alternate network television programming for your media dollars," Winter said.
While stopping short of declaring a boycott of the sponsors, Winter hinted it could happen.
"I assure you that every advertiser on 'America's Got Talent' will be held publicly accountable for underwriting any of the inevitably vile antics of Howard Stern," he said.
"America's Got Talent" is one of the few prime time television shows that offer American families "a brief respite from the otherwise-ubiquitous stream of violent, profane and sexually explicit content," he said.
CNN's Carolyn Sung contributed to this report.