UPDATE: Just got hold of a note from Donaldson confirming that he's forming an exploratory committee to "publically [sic] announce my interest in running for Mayor and do my due diligence, polling and seeing what kind of support I do have out there."

So reports Publicola, which notes the following evidence:

A) Blair Butterworth, a local consultant, says Donaldson is setting up an exploratory committee today to "test the waters." (Before you get too excited, remember the last time that happened?)

B) Butterworth appears to have displaced Christian Sinderman, Donaldson's original consultant. Sinderman also works for Nickels, so he obviously couldn't work for Donaldson too if Donaldson ran for mayor.

Two cautionary notes. First, the last person to form an exploratory committee was Tim Burgess—who bowed out before the week was through upon discovering that no one would give him money. Second, Donaldson actually dumped Sinderman several months ago—since November, he's had consultant McKenna Hartman on the payroll, and before that, it was Laura Ruderman. That makes him look fickle, not focused.