If I remember correctly, provinces which signed on to the HST were also required to stay on board for a period of five years in order to promote stability and spread out administrative costs. (Maybe this only applies to Ontario, can't seem to get the Google-Fu working today).
Regardless, I would actually support keeping the HST and making bigger cuts in income tax on the grounds that a consumption tax like HST is "better" in that everyone pays, it promotes less distortion in the economy (you can reduce purchases of course, but income tax causes economic activity to be shifted away from productive, income producing activities to those which do not attract income tax).
Regardless, Campbell always came across as a weasel, and I won't shed too many tears. If only his pal Dalton would join him....