Check this out:
http://www.snopes.com/politics/quotes/socialism.asp
It was Upton Sinclair in a letter to Thomas and it wasn't phrased in as above. Here's the real text:
"The American People will take Socialism, but they won't take the label. I certainly proved it in the case of EPIC. Running on the Socialist ticket I got 60,000 votes, and running on the slogan to 'End Poverty in California' I got 879,000. I think we simply have to recognize the fact that our enemies have succeeded in spreading the Big Lie. There is no use attacking it by a front attack, it is much better to out-flank them."
Read more at http://www.snopes.com/politics/quotes/socialism.asp#D9tOdvVxh6F65x2U.99

Liberals may not be able to handle the truth, but I think they find misinformation just as annoying as the rest of us.