I found it for $4.95 at musicnotes.com, but I wasn't willing to cough up the $4.95. I've found all kinds of things saying what a significant song it was, but only one very obscure recording.
musicnotes.com does give you the first page for free, so here is the beginning of Verse 1 and Verse 2:

Ism

(Dedicated to the memory of Marcia Brushingham)
Lyrics by Sheldon Harnick
Music by David Baker
from the Broadway Musical Vintage 60

1. I have a daddy who's all the time talking,
Curing the ills of the world;
Communism, socialism, capitalism, nepotism.
Always his tongue is un-.....


2. Marxism, fascism, day after day,
Nothing but isms galore.
I went outside in the alley to play.
I couldn't stand it no.....


Vintage 60 wasn't a big success, I guess. It opened Sep 13, 1960 and closed Sep 17, 1960, after 8 performances. There's a little more information about the show on the Internet Broadway Database, ibdb.com. Sheldon Harnick, usually teamed with Jerry Bock, did the lyrics for a number of musicals, most notably Fiddler on the Roof