Stephen Harper's promise to resign if the Tories lose by just one seat has garnered plenty of attention. But that promise is not at all surprising: since the Conservative vote is the most efficient, losing by "just one seat" likely means losing the popular vote by several points. Trying to hold on to power under those circumstances would have been untenable.
The more significant declaration is, rather, that he expects to govern if the Conservatives win the most seats. This potentially means that, in such a case, if the Liberal and NDP defeat the Tory Throne Speech, Stephen Harper would not view a Liberal and/or NDP government as legitimate, and would ask the Governor General for another election rather than let him ask the Liberals or NDP to try forming government. Note that this could happen even if the Tories come in third in the popular vote - the current projection is not far from that!