"Agree. However, I also believe there were some on the inside of the Nixon administration that assisted the liberals in taking Nixon down."
I agree--that's part of what I was alluding to when I suggested "high-level help". IMO Nixon's Democratic enemies were allied with liberal Republicans who had their own motives for removing Nixon.
Regarding "Witness", one thing Chambers alludes to there that he later considered writing a separate book about was the role of Felix Frankfurter and Dean Acheson in Hiss' promotion and Hiss' reluctance to answer questions Nixon asked him in this area.