The Guardian has an indepth report on Political Blogging (not blogs by politicians). The blogs themselves cover a wide range of political view points.
The article suggests that the phrase “weblog” was probably coined by Barger, posting daily updates in 1997 to his webpage about the Israeli/Palestine conflict. They also suggest that the shortening to “blog” was made by Peter Merholz, as a joke, changing the syllabisation from “web-log” to “wee – blog” in 1999.
Rebecca Blood in her book suggests a different starting point, with Steve Bogart in February of 1997, with Barger not until December.
Which ever version is right, it’s a little removed from the point of this article – about Political Blogging & the influence that it can have.