1) While I still think the idea is basically a non-starter, the idea of a Liberal-NDP merger just keeps getting kicked around. Especially funny is the idea that the Liberals, in courting the NDP, would demand that it renounce socialism and embrace the mixed economy and accept Michael Ignatieff as leader. Sooo... if the NDP were willing to do all that, why wouldn't they have simply all signed Liberal membership cards?
2) Something to ask yourself when considering political mergers: in what year did Harper's Conservatives actually exceed the 2000 combined national vote for the old Alliance and Progressive Conservative parties?
Answer: a trick question--Harper still hasn't exceeded the combined political appeals of those electoral leviathans, Joe Clark and Stockwell Day.
1993, PC & Reform: 34.73%
1997, PC & Reform: 38.19%
2000, PC & CA total: 37.68%
2004, Conservative: 29.63%
The numbers are pretty clear: even with Sheila Fraser's help, the immediate impact of the merger between right and righter was for Harper to underperform the combined vote of Kim Campbell and Preston Manning. (!!!) People remember old Tories like Joe Clark heading for the doors, right?
A similar dynamic would undoubtedly play out in any NDP merger, especially with the existence of the Greens today.
There's some argument to be made for trying to unite the left, but the Liberal conditions that have been mentioned are ridiculous on their face, and a party that was actually capable of any kind of critical inquiry in to its circumstances would realize that.
One poll isn't conclusive, but it's all the data we've got so far so take a look at the Angus Reid poll from two weeks ago: In every merger scenario, the Tories gain -- but they gain the most if Michael Ignatieff is the leader of a merged party, and gain the least is Jack Layton is the leader. The Layton Hypothetical is the closest the merged party comes to actually keeping 100% of the separate party vote.
Now, this is not because Layton is a political genius, but because of something much more basic: Canadian politics has already been half-sorted. There are no more significant electoral gains for the Liberals on the centre-right. Old Joe Clark Tories have, more or less, been convinced that the new Conservatives are not gonna burn the place down, and have made their peace. That's why, in these hypotheticals, the Conservatives gain so little from exiled blue Liberals: there simply aren't that many left in Canada. (There are a shit-ton left in the Liberal Party, of course, and they're incredibly influential, but that's a separate issue.)
If there's going to be a single opposition to the Canadian Conservative party, the votes are going to have to be won on the left, not the right or even the centre. This has been the case for, oh, at least four years. Whether the Liberals are ready to learn this lesson or would instead prefer to lose another election and then blame the rest of us for not jumping on the Ignatieff bandwagon, is a question I leave for you.