Etymology 1 
- (US, idiomatic) The competitive process in which a political party selects their candidate, especially presidential; a primary election via caucus.
- 1993: Mr. Gingrich, who is now the minority whip, announced last week that he had rounded up more than 100 commitments from House Republicans for the caucus race to come after the election next year. (New York Times, October 16, 1993, "Solomon Drops Out of Race To Be G.O.P. House Leader")
- (US, idiomatic) A political competition; the game of campaigning and one-upmanship to get votes and be elected.
- 1993: [...] she was backing southern moderate John Spratt in his strong but unsuccessful caucus race for Budget Committee chairman. (M. Barone, G. Ujifusa, R. E. Cohen, The Almanac of American Politics 1994, National Journal, 1993, p. 176)
Etymology 2 
From caucus (“regular party committee meeting of elected MPs”) + race (“contest between people”); a reference to Lewis Carroll's Alice's Adventures in Wonderland, chapter III "A Caucus-Race and a Long Tale", being a nonsensical satire thereof: all participants have to run in circles until until an arbitrary end is called and everyone is declared a winner; Alice has to give prizes to them all, and being declared a winner too she is solemnly taken and awarded back her own thimble.
Alternative forms 
- caucus-race, Caucus-race (original text), Caucus-Race or Caucus Race (erroneously)
- (originally UK, idiomatic) A laborious but arbitrary and futile activity; an activity that amounts to running around in a circle, expending great energy but not accomplishing anything.
- 1955: With the dominant figure in U.S. politics forced to the sidelines for—perhaps—the rest of the year, the national political situation last week began to take on the unreal air of the Dodo's caucus race. (Time magazine, October 17, 1955, "The Dodo's Dance")
- 1975: The American economic system is beginning to resemble the caucus race in Alice in Wonderland. Is it not something of a contradiction to cut taxes to facilitate the resurgence of buying power that will increase the demand for appliances and, especially, vehicles —and at the same time enforce a reduction in demand for the petroleum fuels that must drive the cars and power the machines that will manufacture the appliances? (Time magazine, February 17, 1975, "To the Editors" by John Rossouw from Australia)
- 1997: A more free and easy attitude prevailed in selecting research topics than today, when the funding squeeze keeps most academic scientists in a tight caucus race of grant getting and paper production that precludes forays into risky serendipitous pursuits. (Christopher Scholz, Fieldwork: A Geologist's Memoir of the Kalahari, Princeton University Press, 1997 (ISBN: 0-691-01226-1), Chapter 1)
- A win-win system; a positive system in which everybody wins.
- 1996: Encourage caucus race resourcing: [...] That is, the resourcing of the players would need to resemble the “caucus race” in Lewis Carroll's Alice in Wonderland – a race in which all the contestants won prizes. The best-known institutional arrangements for resourcing all legitimate comers in a regulatory system is the “subsidiary” doctrine [...] Ressources are not necessarily to be equated with cash: and indeed an alternative way of structuring a “caucus race” is for government to promote the transfer of talent among different institutions [...] (Christopher Hood & David K. C. Jones, Accident and Design: Contemporary Debates in Risk Management, Taylor & Francis, 1996 (ISBN 1857285980), p. 224)