The president's responses to allegations against Republican candidate Roy Moore have been inconsistent at best, perhaps in no small part due to his own conflicted history with accusations of sexual impropriety.
A recent New York Times report sheds some light on the issue, including the fact that Trump has twice denied his own voice on the tape many thought would cost him the presidency:
"But something deeper has been consuming Mr. Trump. He sees the calls for Mr. Moore to step aside as a version of the response to the now-famous “Access Hollywood” tape, in which he boasted about grabbing women’s genitalia, and the flood of groping accusations against him that followed soon after. He suggested to a senator earlier this year that it was not authentic, and repeated that claim to an adviser more recently. (In the hours after it was revealed in October 2016, Mr. Trump acknowledged that the voice was his, and he apologized.)"