| A stalking horse was originally a horse trained for the purpose of providing mobile cover for game hunters. The recognition and avoidance of predators being a primary concern of animals in the lower reaches of the food chain, most wild prey animals will flee from any humans they see, meaning that hunters cannot openly approach ("stalk") their quarry. Prey animals will recognize calm, herbivorous horses, however, as nonthreatening. Stalking horses would accompany hunters in the wild and stand between the human predator and his prey, hiding the hunter from view. Hunters could in this manner create cover wherever they desired, and could maneuver the horse so as to close with their prey while remaining hidden.
By analogy, the term "stalking horse" is used to describe any idea or entity that is employed less as an end unto itself than as cover for another, more threatening or unpopular, idea or entity. Unsurprisingly, the term is predominantly used in reference to politics and public policy, considered among the most predatory fields of modern human endeavor.
For example, the successful campaign to have legal prohibitions on sodomy declared incompatible with the U.S. Constitution, culminating in Lawrence v. Texas, was seen by some observers as a stalking horse for the expansion of civil marriage to same-sex couples. Not without cause, it might seem - though Lawrence did not by itself significantly rile the American citizenry, it was later cited as a basis on which to mandate just such an expansion in Massachusetts' Goodridge v. Department of Public Health, an outcome drawing significant disapproval.
In reference to elections, the term refers to a candidate who enters a race not with the intention to emerge the victor, but rather to split the electorate, ultimately leading to the selection of some other figure. For example, in the Democratic Party's primary for the 2004 U.S. presidential election, Wesley Clark was believed by many to be a stalking horse for Hillary Clinton. | 
