The Parents Television Council (PTC) has publicly urged NBC not to hire Stern, and the organisation later condemned the Peacock Network when Stern officially joined America's Got Talent in December.
The moral values group have purportedly now sent a letter to 91 of America's Got Talent's advertisers urging them not to support the series.
In the letter, which was obtained by TMZ, the PTC cite Stern's controversial comments about former American Idol star Fantasia as proof that he is unfit for family television.
Stern is alleged to have said of the singer: "Hey Fantasia, you're not getting little boys hard. Nobody's beating off to you. Little boys want boners. They want a Britney Spears or a Rihanna."
NBC has not yet commented on the PTC's campaign.
Stern recently touted his abilities as a talent evaluator by insisting that he is the America's Got Talent "judge that America agrees with".
America's Got Talent returns for a seventh season next Monday (May 14) on NBC.
Watch Howard Stern announce his America's Got Talent hiring below: