That’s a very good question. I have a very good answer, butI can’t get too technical with it (my memory of my days in the Navy’s nuclear power program are fading). You can do your own research, using the following as a starting point.
There are five types of force that can act at a distance (i.e., no physical contact). You mentioned one of them: electrostatic force. Magnetism is another, and gravity is a third. The other two are the “strong nuclear force” and the “weak nuclear force.” These two have a greater impact than the electrostatic repulsion from protons close to protons, but only within a short distance. That’s about as far as I can take you.