The problem is that most of the remaining 38 percent may not vote for the Liberal party, but they will vote liberal (small "l") -- not for the Conservatives. True?
The Conservatives seem to plateau at 30 per cent (give or take) in the polls. I can't recall them ever being higher than that. So, if I understand your question (and I think I do), you're right.
There are three left-wing parties, including the Bloc, who divide about 65 per cent of the vote.