I would add a few points there, Cue.
I think the right-wing drift began much sooner than under McLaughlin. I think it was a tendency that goes back to the days of David Lewis, when the notion of party loyalty and fear of Communists was used to transform the CCF from a somewhat nebulous movement into a more rigidly controlled organizational structure. What we've seen over the years, I think, is the end result of that: a party that has virtually no ideology but demands total loyalty to whatever the group consensus is at a particular moment. I don't think Lewis or any of the other back room people intended this to be the case. Merely that their actions set forth a chain reaction of events that created the climate of culture in the NDP that we see today.
McLaughlin herself was the victim of a number of forces that were working against her as well not the least of which was the rise of the Reform Party. Reform's success, at least in Ontario, was partly the effect of the erosion of the working class base in Ontario and the failure of the parliamentary left to provide an adequate response to the restructuring of the economy that began in the early 90s.