Definitions:•An adherent to a party or faction; A fervent, sometimes militant, supporter or proponent of a party, cause, faction, person, or idea;
•a fervent and even militant proponent of something
•devoted to a cause or party
A source.
Anti-Harperism (lacking a better word to call it) is a cause, which you have in your own post and in the list of definitions above in mine. Being partisan only requires you to be a fervent supporter or an idea, or a faction. It does not necessarily mean that you must be an ardent backer of a specific group, since you can also be an ardent backer of ideals contrary to that group.
Partisanship can be loosely translated to "ardent, biased support" of anything mentioned above. I don't wish to call anyone partisan here, I just wanted to come in and quickly remark on the use of the term "partisan." One of the larger problems on discussion boards is the ability for words to be misused, especially misused innocently, and I hate to see future discussion troubled with semantics.
Hope I didn't offend anyone, and sorry for the tangential post!
EDIT @ below: Oh, now I feel like a douchebag.
