Congress has already issued subpoenas that just get ignored, or if they do appear they say they don’t recall or can’t speak to an ongoing investigation. They blow congress off regularly, and all congress can do is hold them in contempt or issue a sternly worded letter.
It’s a joke - they are unaccountable. Prove me wrong.
Re: 78 - in this hyper political environment, I’m not sure why you would think the Executive would comply with Congressional subpoenas.
And regardless, it’s been going on since the 1790’s. President Washington refused to comply with a House Resolution that requested information regarding the negotiation of the Jay Treaty. Or the House requesting information from President Monroe (and Monroe refusing to provide) in 1825 over the Stewart Incident. And on, and on.
Impeachment is one option and is in part a political solution.