“Politics is the art of postponing decisions until they are no longer relevant” is usually credited to French Radical politician Henri Queuille (1884-1970). “His (Henri Queuille—ed.) prescription for government, in his own words, was ‘Put aside all decisions until they are no longer relevant’” was cited in print in 1957.
 
It’s possible that the saying began with a British prime minister. “M. Queuille shared the un-heroic view of a pre-war British prune minister — that ‘the art of statesmanship is to postpone issues until they are no longer relevant’” was cited in 1958. “The art of statesmanship is to postpone issues until they are no longer relevant” was credited to British prime minister Stanley Baldwin (1867-1947) in a 1976 book.
 
   
Wikipedia: Henri Queuille
Henri Queuille (French: [ɑ̃ʁi køj]; 31 March 1884 – 15 June 1970) was a French Radical politician prominent in the Third and Fourth Republics. After World War II, he served three times as Prime Minister.
 
Wikiqute: Politics
Government bureaucracy
Politics is the art of postponing decisions until they are no longer relevant.
. Henri Queuille, The Bureaucrat (1985).
   
Google Books
As France Goes
By David Schoenbrun
New York, NY: Harper
1957
Pg. 118:
His (Henri Queuille—ed.) prescription for government, in his own words, was “Put aside all decisions until they are no longer relevant.”
 
Google Books
Politics in Post-War France:
Parties and the Constitution in the Fourth Republic
By Philip Maynard Williams
London: Longmans, Green
1958
Pg. 35:
M. Queuille shared the un heroic view of a pre-war British prune minister — that “the art of statesmanship is to postpone issues until they are no longer relevant.”
 
Google Books
The Fall of Lloyd George;
The Political Crisis of 1922
By Michael Kinnear
Toronto, ON: University of Toronto Press
1973
Pg. 220:
During this period Baldwin hesitated on many important occasions, after the manner of the French Radicals of the period, whose view seemed to be that the art of politics lay in postponing decisions until the problems were no longer relevant.
 
Google Books
Nine Days that Shook Britain:
The 1926 General Strike
By Patrick Renshaw
Garden City, NY: Anchor Press
1976, ©1975
Pg. 93:
“The art of statesmanship,” he (Prime Minister Stanley Baldwin—ed.) once confided in a revealing phrase, “is to postpone issues until they are no longer relevant.”
 
Google Books
Politics in Gaullist France:
Coping with Chaos
By Charles Hauss
New York, NY: Praeger
1991
Pg. 14:
Philip Williams’s description of Henri Queuille, a one-time premier and perpetual minister during the 1940s and 1950s, is typical of what most usscessful politicians were like: “Queuille believed, like Stanley Baldwin, that the art of statesmanship is to postpone issues until they are no longer relevant” (Williams 1964: 36).
 
Google Books
Dean Acheson:
A Life in the Cold War
By Robert L. Beisner
New York, NY: Oxford University Press
2006
Pg. 489:
A new coalition under Henri Queuille would not form until 10 March, confirming Queuille’s belief that “politics is the art of postponing decisions until they are no longer relevant.”