The breach prompted immediate speculation about cracks in what has until now been a remarkably united movement.
In their ad, the leaders of the four anti-abortion groups say Mr Dobson was wrong to see last April's supreme court decision as a victory. The verdict banned a particular procedure for terminations later in pregnancy, which the anti-abortion movement has labeled "partial birth abortions".
The campaign against that particular procedure has been a rallying point in the anti-abortion movement. Last month's decision was also seen as an indication of a shift to the right on the supreme court following two appointments by President Bush. Opponents of abortion now believe it could soon be possible to overturn the decision legalizing abortion.
However, yesterday's ad argues that the ban on late abortions will not reduce terminations. Instead, the ad says the ban will simply encourage doctors to find other methods for such terminations.
"Dr Dobson, you mislead Christians claiming this ruling will 'protect children.' The court granted no authority to save the life of even a single child," the ad said. It also called on Mr Dobson to repent.