Aggresive Behavior

I have a 33 month old son who has been acting out aggresively since he was 14 months.  When he was 14 months old, I had a second child, so his behavior was normal as he was jealous and given his age.  It got better for a while and now, it has definitely escalated and now he says he wants to "push babies, push kids, and push everyone."  He actually says he wants to make them cry.  He also tells other kids, "get off of me" when they are no where near him and not even paying attention to him.  I have used time outs for up to 5 minutes consistently and it does not work.  I have also tried spanking him just to see it I would get a better result, this does not work either.  He does not seem sorry.  I can't understand why he has so much aggression.  I have tried talking to him and saying don't you want to be a good boy - good boys don't push kids.  I say, don't you want to make other kids smile and laugh.  I tell him you don't like crying and if you push kids it will make them cry.  He definitely does empathize with other kids and babies when they are sad - he says, "oh they are sad" and seems to feel sorry for them.  But he has this really mean streak and doesn't seem to care if others don't like him.  He was in preschool for 6 months, he did not push others in the beginning but toward the end it got really bad.  I don't know what to do.  I feel like I have been battling this issue for such a long time and it should be solved especially because he is almost 3 and I would like to put him back into a preschool program but I am scared that he will bully all the other kids.
Any answers or help would be appreciated.

[Kevin Kennedy, Ph.D.]

It will be prudent for you to seek an evaluation by a child psychologist or other pediatric mental health professional. Such behavior in a nearly-three-year-old can indicate a number of things: childhood behavior problem, impulse control disorder, mood disorder, among others. It is very important to settle on a systematic approach to behavior management, and the foundation of such a program should be immediate time out when any aggressive behavior occurs. Children of this age are learning about impulse control. YOu are saying some sensible things to your son, but don't expect a  child so young to be able to integrate what you are saying. Actions speak louder than words, as you know, so your behavior management tactics will be a crucial help. But try not to handle this on your own - seek an evaluation so you can benefit from the perspective of the menatl health/behavioral health clinician.