The Lib Dems have lost 7 in 10 of their voters. Where have they gone?

The party are keeping hold of around 30 per cent of its voters, with 30 per cent switching to Labour and 40 per cent split between the other three parties.

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The headline polls tell the cost of coalition. After winning nearly 24 per cent of the vote in 2010 the Lib Dems are now languishing on less than 8. But where have all those voters gone and who might they hand the election to?

The vote has split five ways, but put more simply it has split into three: around 30 per cent is staying Lib Dem, 30 per cent is going to Labour, and 40 per cent has drifted to the other three parties.

More specifically, the Lib Dems are holding onto 28 to 34 per cent of their voters, Labour have been gifted 29 to 31 per cent, 13 to 15 per cent has gone to Ukip, 11 to 15 per cent to the Tories, and 7 to 14 per cent to the Greens.

These findings show how varied Lib Dem voters were in 2010. They were a mixture of the party’s left-leaning, former SDP bloc (the 40 per cent or so now voting Labour or Green), a more centre-right group (most of those staying Lib Dem, and those now Tory) and a protest vote (the part now voting Ukip).

Those are the numbers we can find in polls by YouGov, Ashcroft and Populus – the three most prolific British pollsters. They were compiled by averaging the “sub-breaks” of Lib Dem voters across a series of the most recent polls by each pollster. [1]

Three of the other regular pollsters – ComRes, ICM and Ipsos MORI – broadly agreed with these numbers. Only Survation’s are very different. Their most recent poll, which made headlines for putting Ukip on 25 per cent, suggested 47 per cent of Lib Dem 2010 voters would vote Ukip, which is three times more than any other pollster and seems unlikely.

It makes sense that 10-15 per cent of the Lib Dem 2010 vote was a protest, but it’s hard to think half of it was, or that half of those voters would flock to Ukip when all the other pollsters think two-thirds of them will vote Labour or Lib Dem.

When ComRes experimented with prompting for Ukip, as Survation do, they came up with a similar headline number (24 per cent Ukip) but a more modest figure for 2010 Lib Dems: 24 per cent (against 18 per cent in their non-prompting poll). Our initial estimate of a 30-30-40 Lib-Lab-others split seems fair.

Understanding how the Lib Dem vote has changed nationally helps us examine individual seats. These numbers are the baseline we can use to explain how incumbent Lib Dem MPs are faring so much better than their party, as Ashcroft’s polls show they are.

These MPs are usually holding onto far more of the 2010 Lib Dem vote than the national numbers imply. The swing away from the party is weaker in the seats they hold (which means it will be stronger in the ones they don’t).

As for the consequences of all this, the 30 per cent being gifted to Labour is the reason the party may still be able to form a government next year, despite trailing on the economy and leadership, and winning over few 2010 Tory voters. Miliband's party could take more than ten seats from the party that many of its members dislike more than the Tories.

[1] That’s five YouGov polls, three Ashcroft polls and four by Populus. Dates are detailed in the graphic above.

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