Centripetal force is a contact force and contact forces fall under the electromagnetic force.

Centripetal force is the name given to any force which keeps a body in rotation. It is applied normal to the direction of motion and toward the center of rotation. This force can be either pulling (think a pendulum, the rope supplies the centripetal force) or pushing (think of the amusement park ride that spins and the floor drops). In both cases, something is touching the object in question to provide the force. This is why it falls under the category of contact forces. 

Contact forces also include things like pushing, pulling, and friction, although friction is very complex and cannot be attributed entirely to contact.

Now why aren’t contact forces their own fundamental force? Because nothing ever really touches. When two things ‘touch’, they are actually in electromagnetic equilibrium. The electrons in the atoms of the two objects are repelling each other with the same amount of force as whatever force is pushing the two together. Because of this, all contact forces are actually a result of electrons repelling each other, which falls under the electromagnetic fundamental force.

For more information: Wikipedia, Encyclopedia Britannica, and a helpful StackExchange post.

– Admin Noah