In response to my previous “what if” post on running elxn41 under a preferential ballot, a few blog readers wondered how the election would have turned out had there been a Liberal-NDP merger.

The challenge with that kind of analysis is that we have no real way of knowing what 1 + 1 equals. Even merger proponents are not so naive as to assume every current Liberal and every current New Democrat would vote for a new Lib-Dem Party. The tricky part is figuring out how many would stay home or jump to other parties.

I’ve run these kinds of exercises before, but it doesn’t hurt to update it given the new realities of the day. After all, even though a merger seems unlikely, it will be talked about at various times over the next four years – pretty much whenever columnists or bloggers are looking for something to write about during the otherwise dull life of a majority government.

I decided to go into this exercise using a “best case” scenario for the Lib-Dems. That is, I assume that every Liberal with the Conservatives as their second choice (17%) would vote Conservative and every NDP member with the Greens as their second choice (21%) would vote Green. But everyone else would vote for the new party. This would give the Lib-Dems a retention rate of over 80% – higher than the hold rate of the merged Conservative Party in 2004, despite the CPC being given the gift of Adscam (they held just 78.5% of the combined 2000 PC + CA vote).

Under this scenario, the end result is largely the same as now – a 160-seat Conservative majority and a 144-seat Liberal Democrat opposition.

Of course, this was the best case scenario. If the Liberals lose a quarter of their voters to the right and the NDP lose a quarter of their voters to the left, then Harper leads the Lib-Dems 178 to 125 seats in this restrospective hypothetical.

Perhaps a merger would make sense in the long term. But anyone who assumes it would be a quick-fix for booting the Conservatives just simply isn’t looking at the numbers.