Those unschooled in the Freudian stages of psychosexual development may think that if Trump is fixated in any stage to would be the phallic stage. This is not only a sexual stage, but it is when the superego, or conscience, begins to develop.
However, there is evidence that he is really stuck in a much earlier phase (emphasis added):
Anal Stage (1-3 years)
The libido now becomes focused on the anus and the child derives great pleasure from defecating. The child is now fully aware that they are a person in their own right and that their wishes can bring them into conflict with the demands of the outside world (i.e. their ego has developed).
Freud believed that this type of conflict tends to come to a head in potty training, in which adults impose restrictions on when and where the child can defecate. The nature of this first conflict with authority can determine the child's future relationship with all forms of authority.
Early or harsh potty training can lead to the child becoming an anal-retentive personality who hates mess, is obsessively tidy, punctual and respectful of authority. They can be stubborn and tight-fisted with their cash and possessions. This is all related to pleasure got from holding on to their faeces when toddlers, and their mum's then insisting that they get rid of it by placing them on the potty until they perform!
from Simple Psychology
Those of you have lambasted me because I am a psychotherapist doing distant diagnosis, please and respectfully, get over it. We now have far more information about Trump’s personality based on observed behavior to engage highly informed analysis of why Trump is Trump. Besides, this diary isn’t even a diagnosis. Freud is noticeably absent from anything in the DSM-5.