“Talk is cheap.”
Very cheap.
“to spy on him at his home, to spy on him at his office, and indeed they were spying on the White House itself. They were spying on a sitting president”
I ask out of ignorance: is any of that actually illegal? Does it depend on how the spying was done?
Most jurisdictions have laws against electronic wiretap and those would extend to something as mundane as recording an individual without their knowledge or consent. So yeah, there is a violation of the law.