The usual rule here is that we'll refer to people with the name and indentifiers - such as profession or political party - of their choice. But we won't make that an absolute because of the occasional, if unusual, cases in which people are simply deceptive about such things. Clarity and honesty ought to trump deceit.
King County executive candidate Susan Hutchison has in the current campaigns positioned herself as a political independent and moderate, a stance that's been bought by at least some of the regional mass media. (The Seattle Times, in endorsing her, described her simply as "a political outsider.") But that's disingenuous at best. Washington has no political party registration, but you can tell where a candidate stands by their friends, and Hutchison's are from Republican and conservative circles. Not a point to play up in a King County race, perhaps, but such are the facts.
With that in mind, consider the close alliance between Hutchison's campaign and the Building Industry Association of Washington, which in recent years has been the prime engine in Washington state for Republican and conservative campaigns. Horse's Ass has outlined the most recent connections, ranging from contributions to recent rounds of robocalls around the county. If doubt remained about the nature of Hutchison's independence, that should be enough to erase it.