The term “seminar caller” was coined by conservative radio talk show host Rush Limbaugh by at least July 1996. A “seminar caller” makes an “astroturfed” call to a radio talk show. The caller pretends to be an unbiased regular citizen, but then recites talking points that are contrary to the talk radio host’s political philosophy. “Seminar callers” are also called “plants.”
 
The word “seminar” supposedly comes from Democratic party seminars, but has become effectively outdated by technology. Most talking points are now from emails and political blogs and political websites, not from seminars. The term “seminar caller” is still used, especially among conservative radio talk show hosts.
 
 
Wikipedia: Seminar caller
A seminar caller is a coined phrase for someone who mainly telephones conservative radio talk shows for the purpose of astroturfing, which is the mass promotion of a particular product, service, or opposing political point of view as if it were genuinely spontaneous, or grassroots. There is no evidence that there are any actual seminars that exist.
 
Many of these supposed seminar callers try to portray themselves as regular people, claim to agree with the host’s point of view, then begin to read a contrary opinion from an agenda or list of talking points widely circulated by a group or organization who oppose the views of the host.
   
Seminar callers get their name from the seminars they supposedly attend to learn how to most effectively get their message on the air. However, faxes, e-mails and newsletters are more common modes of disseminating astroturf messages to seminar callers.
 
Before the 2004 U.S. presidential election, seminar callers began to tell more elaborate stories to establish credibility, behaving as if they were actors playing the role of someone with beliefs opposite of their own, in an attempt to erode the opposing candidate’s “base” of political support.
 
The term “seminar caller” was most likely coined by conservative talk radio host Rush Limbaugh, but is in wide use among talk show hosts and audiences.
     
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From: .(JavaScript must be enabled to view this email address) (John Switzer)
Date: 1996/07/04
Subject: Summary Wed 7/3/96
   
Unofficial Summary of the Rush Limbaugh Show
for Wednesday, July 3, 1996
by John Switzer
(...)   
When Rush gets his “seminar callers” from the DNC, they never want to talk about character but about the “issues.”
 
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From: .(JavaScript must be enabled to view this email address) (Kenneth Otto)
Date: 1996/07/09
Subject: TV 04 July 1996
 
Unofficial Summary Of Rush Limbaugh The TV Show        
By Kenneth Otto.  Email comments & corrections to:
.(JavaScript must be enabled to view this email address)
Program date - Thursday, July 4, 1996
Independence Day - America’s 220th Birthday
(...)   
Rush talks about the callers to his radio show which Rush refers to as “seminar callers.”  Seminar callers are people who pretend to agree with Rush, claim to have
listened and agreed with Rush for years, but want Rush to stop picking on Clinton so much because it is helping Clinton in the polls.  Rush does not agree with them.  Rush has seen memos from the Democratic party which invite people to call and act this way - it is as if they went to a seminar on how to attack talk radio.
   
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From: .(JavaScript must be enabled to view this email address) (Robert Hubby)
Date: 1996/07/27
Subject: Re: Rush Takes It In The Butt Today… 24 July 96
 
I take it that he was some sort of Liberal Moron, or one of the Seminar callers (The radio version of “Buttman”) and Rush let him natter on for a half hour or so.
     
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From: .(JavaScript must be enabled to view this email address) (PhoebeZ)
Date: 1999/01/15
Subject: Paranoids in radio
 
Rush Limbloob got a call from the obsessed Pat Buchanan fan that always calls NY radio shows and then a liberal that brought up “Iran contra.” At first he complained to the screener, “You got to watch for the crap goin on out there.” Later on he decided that the TWO callers that disagreed with him were “plants and seminar callers.”
 
6 November 2002, Boston (MA) Herald, “Election 2002” by Howie Carr, pg. 6:
Democrats - Shannon O’Brien seminar callers, to be specific - have been much more worried about poor Jim these past few weeks, not to mention Jane Swift, ...
   
Google Books
If It’s Not Close, They Can’t Cheat:
Crushing the Democrats in every election and why your life depends upon it
By Hugh Hewitt
Nashville, TN: Thomas Nelson Publishers
2004
Pg. 168:
These are the fabled “seminar callers” that Rush exposed years ago, the “plants” of the talk radio world, and I love them. Seminar callers pass themselves off as “friends” or “allies” but want to give a seminar on the failings of the officeholder or candidate they purport to support.
 
13 September 2005, Bangor (ME) Daily News, “Lessons of Katrina,” pg. A10:
The liberal seminar callers and letter writers are in overtime hitting their “Blame Bush” buttons.
 
LewRockwell.com
March 24, 2006
An Open Letter To Rush Limbaugh
by William R. Tonso
(...)
Of course, in your great wisdom, you surely think that I’m the print equivalent of one of those “seminar callers” you claim are always trying to smuggle their liberal views on your show under the guise of conservativism.
 
Ace of Spades HQ
February 25, 2010
Organizing for America Begins Astroturf/Seminar Caller Campaign
Wow, these guys sure do have a lot of grassroots, bottom-up, self-starting energy on their side.