While I loathe the antics of Cronkite, who is to blame for losing Vietnam? If Cronkite was the mouthpiece for the Johnson Administration and CIA Cronkite was merely the tool who relayed the message they wanted the North Vietnamese to hear.
Don't confuse the Johnson administration (or any presidential administration) with "official" Washington. Presidents and administrations come and go like clockwork. Official Washington is permanent -- it stays in the government offices, in the law firms and in the news rooms. They work together, cover for each other, and they are the ones who make or break presidents and policies.