For some time, I've been trying to find good polling from the passage of Medicare. According to Greg Sargent, though, the Democrats beat me to it:

In a last-minute effort to stiffen Dem spines, senior Dem leadership aides are circulating among House Dems some polling numbers from the 1960s that underscore how controversial Medicare was in the months leading up to its historic passage.

Dem leadership staff is highlighting a series of numbers from 1962 on President John F. Kennedy’s proposal. In July of that year, a Gallup poll found 28% in favor, 24% viewing it unfavorably, and a sizable 33% with no opinion on it — showing an evenly divided public.

A month later, after JFK’s proposal went down, an Opinion Research Corporation poll found 44 percent said it should have been passed, while 37% supported its defeat — also showing an evenly divided public.

Also in that poll, a majority, 54%, said it was a serious problem that “government medical insurance for the aged would be a big step toward socialized medicine.”

After Lyndon Johnson was elected, a Harris poll found only a minority, 46%, supported a Federal plan to extend health care to the aged. Today, of course, Medicare is overwhelmingly popular.