There are no laws about carrying near a candidate. The security detail establishes a zone around the candidate inside of which they do not permit anyone without prior approval and without some sort of search - couldf be anything from a TSA grope to a quick look to see if your eyes are glazed worse than a Krispy Kreme donut. At the sight of a gun carried by a non-leo, let alone hearing the word "gun", they are going to go into some sort of protective response dance. The higher up the political food chain the candidate is the more vigorous the dance will be.
There are a bunch of federal laws about threatening a candidate, and I have no idea how the Secret Service applies them to otherwise-lawful OC/CC around their principle. There may be state laws as well but I just have never bothered to check.
Outside the "safe" zone you can expect to be rousted, but may not have to actually kiss the pavement while imitating a soaring eagle. Again, whateve lawsr the protective detail bases their behavior on will apply, to some extent, outside the "safe" zone.
I'm not sure that our dashing young videographer would be willing to film someone who volunteered to walk up to someone on the protective detail and ask them a few questioms to help clarify the issue for the rest of us -- and he's got some excellent telephoto lenses he would probably think of using if he did agree to video the event.
stay safe.
