1.  At the beginning of Harper's term it was a minority govt and he had to run a deficit to keep in power.
2.  Then the world financial crisis.  
3.  A GST cut increased disposable income and ultimately more NGO jobs.  The question, was it great enough to increase tax revenue to offset the GST revenue loss.  What so many economists do not understand, (on both sides) -- Tax increases do affect NGO jobs, AND Tax decreases do not create as many jobs as predicted and there is time delay on tax decreases.