The Pundits' Guide's electoral database is an amazing resource, and I've used it to figure out which ridings' incumbents aren't running. I might have missed some, but there are at least 20 such constituencies. Here they are, with the incumbent party and its margin of victory in 2008.
Prince Edward Island
Charlottetown (L, 18)
New Brunswick Southwest (C, 38.8)
Brome--Missisquoi (B, 2.4)
Gaspésie--Îles-de-la-Madeleine (B, 13.1)
Haute Gaspésie--La Mitis--Matane--Matapédia (B, 1.9)
La Pointe-de-l'Île (B, 40.1)
Laval--Les Îles (L, 16.9)
Marc-Aurèle-Fortin (B, 21.1)
Kingston and the Islands (L, 6.6)
Mississauga East--Cooksville (L, 17.6)
Scarborough--Rouge River (L, 36.1)
Lethbridge (C, 52.7)
Calgary Centre-North (C, 41.2)
Burnaby--Douglas (N, 1.7)
Delta--Richmond East (C, 33.7)
Chilliwack--Fraser Canyon (C, 43.6)
Esquimalt--Juan de Fuca (L, 0.1)
Kootenay--Columbia (C, 36.9)
Okanagan--Coquihalla (C, 41.5)
Prince George--Peace River (C, 46)
As you can see, of these 20 ridings, 8 were held by Conservatives. However, the Tories won each of these by at least 33%, so they are not in danger.
Of the 6 Liberal ridings, only Scarborough--Rouge River is as solid. Charlottetown, Laval--Les Îles and Mississauga East--Cooksville appear relatively safe as well, as they are all in traditionally Liberal areas. Kingston and the Islands could well switch: the gap in 2008 was only 6.6%, and the outgoing MP Peter Milliken, as Speaker of the House, is well-known and respected. It's difficult to tell how big an effect his departure will have, especially because he has held the seat since 1988 and because there are no similar ridings close by.
Esquimalt--Juan de Fuca is a special case, which has been mentioned on this blog as well as on BC Iconoclast and Too Close To Call. Keith Martin has represented this riding since 1993, but first as a Reform and Canadian Alliance MP. Before his switch to the Liberals, his vote share was roughly the same as his party's in BC, while the NDP scored a few points better than provincewide, and the Liberals, a few points worse. Martin then won three close three-way fights in 2004, 2006 and 2008; he was never comfortably elected as a Liberal despite his personal popularity. With Martin gone, it appears unlikely that this riding will remain Liberal.
Of the five Bloc open seats, La Pointe-de-l'Île is very safe, and Marc-Aurèle-Fortin should be as well. Gaspésie--Îles-de-la-Madeleine would have been threatened had Ignatieff connected in Québec, but that is not the case. The remaining two seats, Brome--Missisquoi and Haute Gaspésie--La Mitis--Matane--Matapédia, both have a significant chance of going to the Liberals. Not only were both very tight races in 2008, but also, in both cases, the Liberal candidate is a former MP or MNA.
Finally, the NDP open seat, Burnaby--Douglas, is also precarious. Bill Siksay, the outgoing MP, was first elected in 2004, and has won all three elections by less than 3%. It looks like the NDP gets around 35% no matter what. When the Liberals do well in BC, they end up being the main contender, a few points in front of the Tories. When the Grits collapsed in 2008, it seems like more of their voters went Conservative than NDP, allowing the Tories to challenge Siksay. The Liberals are now doing better than in 2008, but not as well as in 2004 or 2006 in BC. This may be the recipe for an NDP hold.
Given the above analysis, I will adjust my model for two ridings only:
- Esquimalt--Juan de Fuca: Given current levels of support, I will move this seat to the Conservative column. This seat goes NDP if it comes within 5-10% of the Tories in BC. I will set a precise threshold if the NDP comes within 10% of the Tories in the projection average. (Right now, the gap is over 17%.)
- Kingston and the Islands: I will give the Liberals a 4% penalty here, so the Tories need to increase their provincial lead by 2.6% instead of 6.6% in order to claim the seat. Currently, this doesn't make a difference, although it would have earlier in the campaign and still could later on.
The other three ridings will not be subject to adjustment. For the two Québec ridings, this is because the retiring MPs there do not have a high profile, and because the Bloc being essentially a protest party, the local candidate likely matters less. As for Burnaby--Douglas, the above analysis points to circumstances favourable to the NDP. However, if the Liberal vote collapses or surges, I will revisit this case.
All this is, of course, completely arbitrary. I've tried to be parsimonious in limiting these ad hoc adjustments to two ridings. Normally, I wouldn't have bothered, but the Conservatives are sufficiently close to the magic 155 that this could become relevant.
The new projection is therefore:
CON - 147
LIB - 79
BQ - 47
NDP - 35
For the rest of the campaign, when plotting projection trends, I will retroactively increase the Tory count by 1 and reduce the Grit count by 1 throughout in order to improve consistency. This will account for the Esquimalt--Juan de Fuca change. I will not retroactively account for the Kingston and the Islands change because, unfortunately, I have not kept records that allow me to determine when that seat would have been in the Conservative column.