“Politicians are the lowest form of life on earth”

The book The Unknown Patton (1982) by Charles M. Province contains the following quote by United States Army General George S. Patton (1885-1945):
 
“Politicians are the lowest form of life on earth. Liberal Democrats are the lowest form of politicians.”
 
It is not known if the quotation is accurate—the quotation appears in no other source. Patton’s alleged quotation has become popular with conservatives and Republicans.
   
“That government is bad and that politicians are the lowest form of life” was cited in a 1949 book.  U.S. President Harry S. Truman (1884-1972) wrote in a diary on May 22, 1945 that a professional liberal is “the lowest form of politician.” George S. Patton died in December 1945, likely not knowing either quotation.
 
   
Wikipedia: George S. Patton
George Smith Patton, Jr. (November 11, 1885 – December 21, 1945) was a United States Army general, best known for his command of the Seventh United States Army, and later the Third United States Army, in the European Theater of World War II.
 
Google Books
The College Anthology
Edited by Walter Blair and John C. Gerber
Chicago, IL: Scott, Foresman
1949
Pg. 294:
THE PROPER STUDY   OF MANKIND
That men won’t work unless they have to.
That any man willing to work can get a job.
That business makes all our employment.
That the open shop is the American way, and labour unions are foolish, if not wicked.
That all strikes are due to trouble-makers.
That the individual must fend for himself and in the end gets what he deserves.
That the small business man is the backbone of America.
That women cannot be expected to understand public problems.
That the American form of government is the final and ideal form.
That government is bad and that politicians are the lowest form of life.
 
Google Books
The Unknown Patton
By Charles M. Province
New York, NY: Hippocrene Books
1982
Pg. 99:
“Politicians are the lowest form of life on earth. Liberal Democrats are the lowest form of politicians.”
 
28 March 1988, Indiana (PA) Gazette, “Vote against a Democrat” by Charley Reese, pg. 2, col. 1:
I do not understand how the American people can tolerate the Democrats in the Congress.
 
They remind me of General Patton’s observation that ... politicians are the lowest form of life and liberal Democrats are the lowest form of politicians.
 
Google Books
Off the Record:
The Private Papers of Harry S. Truman
By Harry S. Truman
Columbia, MO: University of Missouri Press
1997
Pg. 35:
DIARY
May 22, 1945
(...)
Told Davies I’d sent Hopkins because I trusted him and because he had been Roosevelt’s messenger to Russia on a previous and similar occasion, that Hopkins was noted [as] an advanced “Liberal” but not a professional one (I consider the latter the lowest form of politician), that he had horse sense and knew how to use it.
     
The Fine Report
Gen. George S. Patton: “Politicians are the lowest form of life on earth. Liberal democrats are the lowest form of politicians.”
Published on June 19, 2013, by Editor
 
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Politicians are the lowest form of life on earth. Liberal Democrats are the lowest form of politicians. #quote George S. Patton
8:27 AM - 24 Apr 2014