I've been saying he's a narcissist all along. Which to me is a form of mental illness.
Here are the symptoms of being a narcissist according to Wiki:
Symptoms of this disorder, as defined by the DSM-IV-TR, include:[1]
Expects to be recognized as superior and special, without superior accomplishments.
Expects constant attention, admiration and positive reinforcement from others.
Envies others and believes others envy him/her.
Is preoccupied with thoughts and fantasies of great success, enormous attractiveness, power, intelligence.
Lacks the ability to empathize with the feelings or desires of others.
Is arrogant in attitudes and behavior.
Has expectations of special treatment that are unrealistic according.
Other people are questioning his mental stability as well.
Psychologist Concerned About Mental Stability of President: Obama May Not Be