What makes a partisan?

Instapundit:

Meanwhile, further down in the comments, Oliver Willis calls me "partisan." In the sense of supporting a candidate, sure, since I pretty much gave up on Kerry quite a while ago, but not in the sense of supporting a party regardless of candidate.

Since when did having an opinion make one a partisan hack? It seems to me to be an odd inversion. Generally, partisan hacks tailor their public opinions to suit the need of the campaign/candidate. Like a "family values" conservative defending Newt's adultery or an "I believe Anita" liberal trashing Paula Jones/Willey/Lewinski, etc. For the opposite of hackery, see Michelle Malkin's defense of John Edwards today.

I am always amused to see the people call Instapundit a rigid conservative or a Republican flack. I know conservatives. I grew up with rigid Republicans (my grandfather voted for Landon and my father went all out for Goldwater). Instapundit is neither a solid conservative (abortion, gay marriage, stem cells, immigration) nor a dependable Republican. (Where is that full-throated defense of Tom Delay and Alan Keyes?)