Four-year-old john is very competitive with his father in trying to gain more attention from his mother. freud would have suggested that john is experiencing:

I believe the answer is: phallic stage of development

In the phallic stage of development, children would started to develop the libido in their eroegneous zone. 
Even thought there is no concrete proof for this, Freud believed that during phallic stage of development, a male child would develop unconscious sexual desires for their mother which cause them to see their father as their rival in having their mother attention.