Michael Lind gives it a try:
The Tea Party will prove transient By Michael Lind Financial Times October 19 2010
^^^^^^
New American political movements come in two varieties: genuine third-party movements and those that just mobilise the base of one of the existing parties. The former transforms an existing party system; the latter reinforces it. And the Tea Party is an example of the latter – so while it has attracted a great deal of attention, it has little long-term potential to transform America’s political landscape.
^^^^^^^^^ CB: Hope it isn't wishful thinking to call the TP transient.
What are Lind's examples of actual historical examples of the "former" - third parties that have transformed the existing party system ? I assume he doesn't include Bolsheviks , Fidelistas, etc.