http://www.slate.com/articles/news_a...ing_horse.html
what is a stalking horse, anyway?
In early 16th-century England, a "stalking horse" was one trained to conceal the hunter walking behind it; the practice allowed human predators to sneak up on their prey without attracting suspicion. But by 1594 the term had also evolved into a metaphor for underhanded political dealing,
In modern political applications of the phrase, a stalking horse is either a candidate used to divert attention from someone else's candidacy, or a candidate who splits the vote of a serious contender,
perhaps unwittingly, and thus benefits a third, better-positioned candidate. By this second definition, Ross Perot was a stalking horse for Bill Clinton in 1992, Ralph Nader was a stalking horse for Bush in 2000, and almost any third-wheel candidate who loses could be termed a stalking horse for whoever wins.
For Democrats, Donald Trump amounts to a kind of divine intervention.
With the Republican Party on an urgent mission to woo Latino voters, one of its leading presidential candidates has been enmeshed for two weeks in a nasty feud over his inflammatory comments about Mexican immigrants.
“They’re bringing drugs,” Trump said in his campaign announcement speech. “They’re bringing crime. They’re rapists.”
http://www.washingtonpost.com/politics/donald-trump-surges-and-democrats-cheer/2015/07/01/895d9e9e-1f5d-
11e5-84d5-eb37ee8eaa61_story.html