The New York Post published lewd photos the former congressman reportedly sent to a woman who is not his wife. One photo shows his son next to him.
If he can't secure 15 percent support before the first debate, he says it's game over.
A poll released Sunday shows the two candidates are just a few percentage points apart.
Trump says he plans to deport criminals "within one hour" of taking office.
The State Department says it won't be able to release the full schedule until the end of the year.