What The First Dummy doesn't get is that you don't have to be a supporter of the Tea Parties to be revolted at the liberals' use of the term "teabaggers." This will erode what support he has left with the left-of-center crowd.
Well, considering that on February 1, 2009 -- FedUpUSA called for people to send tea bags to members of Congress -- "a Commemorative Tea Party" -- that shows where the name of "tea bag" came from... and it was very appropriate as a symbol for what the TEA Party is doing.
So, it makes sense to appropriate the name "tea-bagger" for the party and individuals, considering this big mass action that was done, sending in those "tea bags" ... :-)