It may have been a matter of how I handled the nominations this time around. I didn't even consider that, but you make a good point.
I have found that (in general) most of the left-leaning folks on the board tend to be pretty aggressive in the political category. That's probably fairly natural, since they are attacked so much. I once made Tim a moderator just to help police the political category, but he eventually called it quits because it got on his nerves too much.
As I said in the OP, though, I plan to bring in another round of mods in the not-too-distant future.