I think this is a very insightful email, from a reader:
What helped Reagan was not the actions of the media and the Left in
attacking the war in Vietnam. It was the fact that, after the war was
over, they couldn’t let go of it. Many (perhaps most) American
supported our withdrawal, but with regret. When it was over, much of
the country wanted to forget about it. But the media and the Left dwelt
on it, sometimes celebrated it, constantly rubbed our noses in it.
At the war’s end (for us), Johnson and Nixon got the blame. But those
who could not let go of it came to own it. The long-term consequences
of the Iraq War for the Democrats are probably dependent on their
handling of the aftermath.