An electoral pact between the Conservatives and Liberal Democrats is a question that won't seem to go away. Repeatedly dismissed by Clegg and Cameron (though not always in the most concrete language) the speculation keeps coming back. But, what actually would happen if there was a pact?
At the simplest level, we asked a straight question on how people would vote if there was a pact between the Conservatives and Liberal Democrats, with the Conservatives standing down in seats where the Liberal Democrats were best placed to win, and the Liberal Democrats stand down in seats where the Conservatives are best placed to win. In this scenario, 40% of people would vote for a Coalition candidate and 46% would vote for Labour. If we compare this to our normal voting intention on the same day, which showed the Conservatives on 37%, Labour on 42% and the Liberal Democrats on 9%, a pact certainly doesn't look like a good bet - the support for joint candidates is 6 points lower than the parties separately, and the Labour lead over the Coalition is bigger than over the Conservatives alone.
However, if we look more closely at the figures it all gets a bit more complicated. As you might expect, people who would vote Labour in a normal election have little or no doubt that they'd still vote Labour if the Conservatives and Liberal Democrats entered a formal pact. However, the drop in Conservative and Liberal Democrat support isn't down to defections to Labour or minor parties, overwhelmingly it is just that many Conservative and Liberal Democrat voters say they don't know what they'd do - and well they might, since we don't know what sort of platform this electoral pact would campaign on and who would fight which seats.
A Conservative in a safe Tory seat might very well be unsure what they'd do if suddenly faced with a ballot paper with just Labour and a Coalition Liberal on it. Equally a Liberal Democrat in a Lib Dem seat might be uncertain how they'd react if faced with a ballot paper showing just Labour and a Coalition Conservative. We can make some reasonable assumptions about which party will stand where though - the strongest Tory areas would have Tory candidates and the strongest Liberal Democrat areas would have Liberal Democrat candidates.
The core question then becomes how many Liberal Democrat supporters actually will transfer their support to the Tory candidate, and how many Conservative supporters actually will transfer their support to a Liberal Democrat.
To answer that, we asked the survey a second time and, based on people's constituencies and the result in 2010, we gave them either a scenario of the Lib Dems standing down in favour of the Conservatives, or the Conservatives standing down in favour of the Liberal Democrats.
Even asked like this, the findings need to be laced with heavy caveats. Hypothetical questions are dubious at the best of times, but in this case we don’t know what platform a Conservative-LD pact would be fought upon and whether they would have a joint manifesto. We also don’t know what the repercussions would be of creating such a pact – it would probably change perceptions of the parties and politics in Britain and there is a fair chance it would lead to defections and party splits, further disrupting the political landscape. With all that in mind though, here’s what we found.
In seats where the Conservatives beat the Liberal Democrats in 2010 – that is, the seats that are likely to be contested by the Conservatives in an electoral pact situation – 93% of Tory voters would still be happy to back the Coalition Conservative (the other 7% are presumably those Tories strongly opposed to such a deal, most of whom say they still don't know how they'd react). However, of the current Liberal Democrat voters in these seats, 44% would give their vote to the Coalition Conservative, 15% would instead vote Labour with the rest not sure, not voting or giving their backing to minor parties.
Given how few Liberal Democrat supporters remain in these seats anyway these figures would pretty much even out, giving the Conservatives no obvious electoral benefit from the pact.
Now we turn to the seats that are likely to be contested by the Liberal Democrats in an electoral pact situation – those where the Lib Dems out polled the Conservatives in 2010. There are naturally far fewer of these – only 158 - so the sample size is much, much smaller, but the crude indications are that the Liberal Democrats would retain most of their current support, but would also gain 57% of the current Conservative support in those seats, with the rest going to minor parties, not voting or not sure.
Given the depths that Liberal Democrat support has fallen to, this would make a major difference to their level of support, transforming the chances of them holding a significant number of seats.
At best this can only ever be a straw in the wind given the political earthquake that any electoral pact risks producing, but my tentative conclusions are that the Liberal Democrats have much more to gain from an electoral pact than the Conservatives.