Don't get too excited; Peter Steinbrueck hasn't declared he'll run against Mayor Greg "Invincible" Nickels. However, a recent poll shows that if he did run, he'd have an excellent shot.

Among likely primary-election voters, in a four-way race between Nickels, former city attorney Mark Sidran, and city council member Nick Licata, Steinbrueck comes in second to Nickels with 15.8 percent of the vote to Nickels's 17.3 percent. I don't have the margin of error on those numbers, but I'm guessing those percentages are statistically equivalent.

But it's in a two-way matchup that things get interesting. (A two-way matchup, by the way, is the most likely scenario at this point—no viable candidates to Nickels have come forward so far, Sidran has said he isn't running, and Licata claims he's going to seek reelection.) In that scenario, Steinbrueck wallops Nickels 46.6 percent to 24.1 percent, with 29.4 percent undecided. Among likely primary voters 55 and up (the sub-group that's most likely to vote in an off-year primary election like this year's), Steinbrueck gets an outright majority of 53.2 percent to Nickels's 22.4 percent, with 24.4 percent undecided.

Those are good numbers. Really good. Potentially good enough to overcome the (perhaps irrational) fear that Nickels has all the money in town locked up. Steinbrueck's looking like the best shot Nickels opponents (and bored political journalists) have for an interesting, viable challenger this year. Run, Peter, run!