In U.S. political jargon, a smoke-filled room (sometimes called a smoke-filled back room) is a term for a secret political gathering or round table style decision-making process. The phrase is generally used to suggest an inner circle of power brokers, as at a convention. It suggests a cabal of powerful or well-connected, cigar-smoking men meeting privately to nominate a dark horse political candidate or otherwise make decisions without regard for the will of the larger group.
An early example of a smoke-filled room is the Boston Caucus. A report of a 1763 meeting of this group said, "selectmen, assessors, collectors, fire-wards and representatives are regularly chosen [there] before they are chosen in the town ... There they smoke tobacco till you cannot see from one end of the garret to the other."
The origin of the term was in a report by Raymond Clapper of United Press, describing rumors of the process by which Warren G. Harding was nominated as Republican candidate for the 1920 Presidential Election. After many indecisive votes, Harding, a relatively minor candidate, was, legend has it, chosen as a compromise candidate by Republican power-brokers in a private meeting in room 404 at the Blackstone Hotel in Chicago after the convention had deadlocked.