Yes, it was an issue a year or two later than 1964.
Yes, it was an issue a year or two later than 1964.
What I'm saying is that the Johnson people were indeed using Vietnam as an issue during the 1964 campaign—warning that Goldwater would be too aggressive there. Goldwater, as an anti-Communist, was saying we should fight the Communists in Vietnam as if we meant it, and bomb all the NVA's assets and factories and win the darn thing—instead of pussy-footing around, McNamara style. The Johnson people were saying that this was crazy stuff, that the man is a war-monger. Hence the joke—Johnson started escalating in Vietnam, after saying only a lunatic like Goldwater would do that. Reminds you of Woodrow Wilson's campaign slogan for the election of 1916, after his first term: "He kept us out of war!"
For the '64 election, the Dems framed out their usual position, promising to confront Communist aggression in a nuanced manner by not confronting it. Another element of the campaign was how Goldwater would deal with the Soviet Union itself—asserting that he would get us into nuclear war with his belligerence. I'm sure you remember hearing about the famous anti-Goldwater TV ad showing a girl holding a flower in a field, and then cutting to a mushroom-cloud explosion—warning that Goldwater's extremism would be responsible for atomizing little chirrens and their flowers.