According to the ever popular New Dictionary of Cultural Literacy, "Originally, a small, informal opinion survey. Today, a straw poll is generally a large-scale, scientifically determined public opinion survey based on a random sample of the population. Straw polls are commonly used to test public opinion of candidates running for office."
http://www.bartleby.com/59/14/strawpoll.htmlThe New York Times had this about McCain's ploy:
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Nearly 2,000 Republicans gathered here to listen to six potential presidential candidates and then pick their favorite in a straw poll on Saturday. No matter that it is 22 months until a single Republican votes: the Southern Republican Leadership Conference quickly turned into a swirling political circus, complete with candidates, senators, governors, consultants and television crews tromping through the ornate lobby of the Peabody Hotel.
But on Friday, Senator John McCain of Arizona, one of the party's leading prospective presidential candidates, announced he would instruct his supporters not to vote for him and to instead write in the name of President Bush, as a show of support.
The move left supporters of Mr. McCain's main rival — Senator Bill Frist of Tennessee, who had been looking for a big hometown win — sputtering. And it greatly diminished the importance of an event that was, truth be told, of debatable significance in the first place.
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http://www.nytimes.com/2006/03/11/politics/11repubs.html