Oh, I don’t know, Nixon overwhelmed anti-war McGovern even 4 years after Tet. The Vietnamization of the war actually arguably was succeeding until Watergate and the Democrat betrayal of the South Viet Namese, which was Cronkite’s really destructive act, as far as I’m concerned.
My understanding of events, gleaned several years after the fact, is as follows. We bombed North Vietnam back to the peace table. We negotiated a deal. We had an orderly removal of troops, but for a few at the US embassy. It was understood that we would provide financial aid to our ally, South Vietnam. In case of a conventional invasion by the North, we would provide military assistance.
After Watergate, the new Congress was very Democrat and very liberal. They cut off aid to South Vietnam and passed a law prohibiting military assistance to South Vietnam under any circumstances. This was an open invitation for the communists to resume the war. Two years later, South Vietnam fell.
The US won the war, then abandoned an ally. Liberals did not care. They thought communism would be better for South Vietnam and the region. History has proved them wrong.