Entry in progress—B.P.
 
 
Wikipedia: Smoke-filled room
In U.S. political slang, a smoke-filled room is a secret political gathering or decision-making process. The phrase is generally used to suggest a cabal of powerful or well-connected men meeting privately to nominate a dark horse candidate or make some other decision without regard for the will of the public. The origin of the term is an Associated Press report describing the process by which Warren G. Harding was nominated as Republican candidate for the 1920 Presidential Election. After many indecisive votes, Harding, an unlikely and little-known candidate, was chosen by Republican senators and party power-brokers in a private meeting at the Blackstone Hotel in Chicago.
 
Encyclopedia of Chicago
Smoke-Filled Room
The original smokefilled room was in Chicago’s Blackstone Hotel, where, according to an enduring legend, a small group of powerful United States senators gathered to arrange the nomination of Warren G. Harding as Republican candidate for president in 1920.
 
Meeting at the Coliseum, the convention deadlocked on Friday, June 11. At a suite in the Blackstone, Republican leaders held a series of discussions late into the night. Though leaning toward Harding at that point, participants did not control the convention. But when the Associated Press reported that Harding had been chosen “in a smoke-filled room,” the phrase entered the American political lexicon. Ever since, “smoke-filled room” has meant a place, behind the scenes, where cigar-smoking party bosses intrigue to choose candidates.
     
Dictionary.com
smoke-filled room
A popular expression used to describe a place where the political wheeling and dealing of machine bosses (see machine politics) is conducted. The image originated during the Republican presidential nominating convention of 1920, in which Warren G. Harding emerged as a dark horse candidate.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
 
Google Books
The Yale Book of Quotations
Edited by Fred R.Shapiro
New Haven, CT: Yale University Press
2006
Pg. 187:
Harry M. Daugherty
U.S. politician, 1860-1941
[Remarks by General Leonard Wood in a speech, Toledo, Ohio, 1 Apr. 1920:]
“What a distinguished political leader [Daugherty] recently said in Washington would be done in the 1920 Presidential nomination, namely, that about 2:11 A.M. the nomination would be settled by fifteen or twenty tired men sitting around a table in a smoke-filled room behind locked doors.”
Reported in N.Y. Times, 2 Apr. 1920, Safire’s New Political Dictionary gives a detailed account of Associated Press reporter Kirke Simpson suggesting the phrase smoke-filled room

to Warren G. Harding’s supporter, Daugherty, during the Republican National Convention in June 1920. However, the Apr. 1920 speech above proves that smoke-filled room was used earlier in the year. It appears that Wood meant Daugherty as the “distinguished political leader,” since an article of 21 Feb. 1920 in the same newspaper quoted Daugherty as predicting that “about eleven minutes after 2 o’clock on Friday morning at the convention, when fiftenn or twenty men, somewhat weary, are sitting around a table some one of them will say:‘Who will we nominate?’ At that decisive time the friends of Senator Harding can suggest him.” (Harding was in fact nominated as Daugherty had predicted, including the time, which was approximately 2:00 in the morning.)
 
(OED)
1920 Evening Star (Washington) 14 June 1/2 Harry Daugherty..predicted that
about 2.11 a.m., ‘in a *smoke~filled room’, on a certain night during the
republican national convention, the next nominee would be chosen. 1965 G. MCINNES
Road to Gundagai v. 77 These damp and smokefilled holes. 1979 Now! 21-27 Sept.
74/3 Presidential candidates are not selected by political pros in
smoke-filled rooms these days.
 
 
(PROQUEST HISTORICAL NEWSPAPERS)
14 February 1915, Chicago Daily Tribune, pg. 6:
Candidates have not been required to talk in smoke filled rooms, and they
have not been disturbed by the boisterous conduct of men and boys in the
approaches to the halls.
 
11 June 1920, New York Times, pg. 2:
The home (illegible—ed.) roared approval of the work that had been done by a
few men in a smoke-filled room.
 
 
(http://www.newspaperarchive.com) (“smoke-filled room” and “nominate”)
Lima News Tuesday, June 15, 1920 Lima, Ohio  
...he predicted that about a. a SMOKE-FILLED ROOM” on a certain night,
during…..It was the plan of the Old Guard to NOMINATE Lowden but the Missouri
expose..