The argument is intuitively appealing, but its premise is utterly dishonest. First of all, contrary to myth, Canada's major parties face no meaningful spending restrictions. No, they don't. Advocacy groups may endorse or oppose parties and candidates, but their real goal is to advance a cause over the longer term. The reality is the opposite.
Studies show free-trade spending had no effect on the partisan outcome of the election.
But what the advocacy groups did was advance the issue of free trade and polarize the election around it. And the reality is that the Liberals, once in office, did adopt and extend liberalized trade notwithstanding their 1988 opposition. So successful was this approach that the Mulroney government passed the free-trade agreement as its first and only bill in the following session. That's why the Tories were livid about losing control of the election agenda. To prevent this from happening again, the Mulroney government passed a Draconian gag law.