Ahead of the first debate between Nick Clegg and Nigel Farage tomorrow, many have predicted that both men will win. This is because, as the Telegraph's Benedict Brogan writes in his column today, "the two parties are not competing for voters – they draw support from different ends of the spectrum." In the case of tomorrow's head-to-head over EU membership, this is undoubtedly true; Clegg is bidding for the "inners" (a group larger than the Lib Dems' current base), with Farage bidding for the "outers".
But it's worth noting the degree of crossover between current UKIP supporters and former Lib Dems. A recent study by Peter Kellner, for instance, found that more than 500,000 2010 Lib Dem voters have defected to Farage's party, a figure greater than the number who voted Labour (c. 400,000), who voted UKIP (c. 400,000), or who didn't turn out (c. 400,000). Today's YouGov poll shows that 12 per cent of 2010 Lib Dem voters (excluding don't knows and wouldn't votes) currently support UKIP, a share that matches the number of Tory defectors (12 per cent) and exceeds the number of Labour ones (2 per cent).
That these voters have swung from the most pro-European party to the most anti-European party is less surprising than many think. People in general pay far less attention to policy than most assume and this is especially true of the EU, which does not even make it into the top ten of voters' concerns (it is currently ranked 18th). What explains the swing is UKIP's supplantation of the Lib Dems as the "none of the above" party: the party voters support when they want to kick the Westminster establishment.
With Clegg now framing the Lib Dems as "a serious party of government", he is largely resigned to loss of most of this group. But the Lib Dem to UKIP defectors show that Clegg and Farage will be competing for some of the same voters tomorrow.