I question how long this is to be.
Of course it depends on a few imponderables:
1) Will the NDP lead turn into solid seats on Monday. The trends point to "yes" on this one--but never discount the power of second thought at the ballot box.
2) If the NDP become the official opposition, it will likely be on the back of a decimated Bloc. If that is the case, will the NDP attempt to take power backed by the Liberals? This is a dicey proposition. It worked for Peterson in Ontario, perhaps, because he had won the popular vote and was within 4 seats of the Conservatives. Layton will not have that kind of political mandate.
3) Will this shift left be durable (like the shift to Labour in the early 20th century in Britain) or a one-off (like Bob Rae's government in Ontario)? This is, perhaps, the most imponderable of all. If the NDP seizes power, there could be a strong backlash against a "coalition of losers." On the other hand, if the NDP sit on their hands and allow the Conservatives to govern, they may face the wrath of people who thought they were voting for regieme change.
If the NDP take power, where will they move fiscally? Their platform program needs something in the line of $29bn in program funding, but no source of funds to provide for it. Restoring the GST to 7% and eliminating the corporate tax cuts would be a start, but beyond that, they start to moving into damage territory, where they would not have the Liberals' support. But if they fail to deliver on their platform, what will the expectations of their supporters be?
4) How robust is Layton's health? He has been leader longer than any of the other federal party leaders, and he has had a couple of significant health issues in the last year. The NDP front bench has little depth, and the new arrivals will add almost none. Is there a successor in the wings capable of continuing this surge?
The Prime Minister has held a pretty obvious long game since 2006: demonize the Liberal party by whatever means necessary, and drive the leftist vote to the NDP, making the federal political scene a two party affair after the fashion of Britain in the twentieth century. His read of the Canadian political center is that if faced with the choice between the Conservatives and the NDP, the center will break right, and the Conservatives will become the new default governing party. (And to be honest, I don't think that he is wrong, either).
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--James