Four polling firms have already completed surveys after Thursday's election debate in the UK. Here are the averages, with the change from the average of these same 4 firms' last results before the debate in parentheses:
CON - 35.5% (+1.75%)
LD - 28% (-0.5%)
LAB - 27% (-0.25%)
Note that, based on their last polls before the last debate, these firms had Labour about 1 point higher on average than all 11 firms (that I know of) combined.
According to the BBC's Election Seat Calculator, which assumes a uniform national swing, we would get CON 286, LAB 251, LD 84. Adjusting for problems with a uniform swing in an election with large changes, I expect something like CON 310, LAB 205, LD 105 if current numbers hold.
In the above scenario, the 30 seats belonging to small parties become very important, since the Tories might be able to govern with the support of small parties rather than the Liberal Democrats. A majority is nominally 326 seats this time, but there are complications:
- In the UK, not only the Speaker, but also three Deputy Speakers do not vote; in the previous Parliament, the Speaker and two Deputies were Conservative (the other Deputy was from Labour).
- Sinn Fein does not take its seats; in the 2005 election, they had won 5.
Thus, if the Northern Irish electoral results are replicated, there would be 641 voting members in the House, meaning that 321 votes would effectively form a majority. If the Tories still provide the Speaker and two Deputies, they would need 324 seats (or 323 if you count the Speaker separately) for a voting majority. If they gain the support of the unionist Northern Irish parties, which are right-wing, and if these parties win 10 seats like they did last time, then the Conservatives would need 314 seats (313 not counting the Speaker). All other small parties lean left, and are thus less natural partners for the Conservatives. Finally, the Tories may decide to provide fewer than 3 of the 4 non-voting members of the House, though they will almost certainly still provide the same Speaker, and probably at least one Deputy Speaker.
So this is how the situation for the Tories looks to me, counting the Speaker (and assuming Northern Ireland results remain unchanged from 2005):
322-323: majority through giving up on one or both Deputy Speaker positions
314-321: majority through alliance with Unionist parties
312-313: majority through both of the above
More than 298 or so: need support of at least some left-leaning small parties to govern without Lib Dem or Labour support
Less than 297 or so: require support of Lib Dems or Labour
Currently, the Tories may well be smack in the middle of that 298-323 ambiguous area, although my guess is that they will look for Lib Dem support before trying to woo over multiple small left-leaning parties. The last 4 days of campaigning will be crucial!