Elections don't work to stop things like this. As mentioned, the agencies are far too entrenched. They literally bypass our most sacred laws and structures as if they don't even exist.
Intelligence agencies would certainly would blackmail or suicide any domestic element that poses a serious threat to them, since historically they don't have a problem doing this to random people.
Wait, what gives you the impression that intelligence agencies care about being inconspicuous for stuff like this?
The fact that they suicide people is basically a running meme. There is nothing to hide. Everyone knows that intelligence agencies pull this shit. It surprises no one we all know they will continue to do it.
If sentiment against IA becomes really negative, they'll have a hard time doing particularly egregious stuff. Right now, plenty of people are totally fine with IAs.
If 100% of people think IAs are villainous, IAs will have a hard time recruiting capable people, so they will shrink and be less efficient. It will be easier to litigate against them too, since they have less of an ability to subvert the legal process with fewer people working for them, and fewer people being on their side. Congress will be more able to act and more incentivized to act against them if the rest of the country is united in disliking IAs.
They can elect someone that can give the agencies a hard time. I guess every time that happens though, we get a one term or less president.