I think the media played a bigger part.
It was the first war where there were cameras filming lots of stuff. It brought the images of war to the families at home.
The Zipo fires , and mistreated villagers were too much for the American people.
The protests were a form of light shedders. They brought the horrors to light. Put it in people’s faces.
Sometimes a problem has to be brought into the light, to be seen for what it is,and that it must be eradicated.