With Labour most likely poised to elect Jeremy Corbyn as its next leader this Saturday, it’s worth looking at how he could assemble a winning coalition of voters for 2020. His supporters claim that Corbyn reaches the parts of the electorate—particularly the young—that others can’t. They have identified three pools of potential voters who turned their backs on Labour in 2015; people who voted for other parties of protest, those who did not vote at all and the young (often well-represented in these first two categories). Almost anyone, in fact, who didn’t vote Conservative. But is this enough?

Labour’s failure to monopolise the protest vote clearly cost it at the general election—in England and Wales alone, UKIP’s vote share was larger than the winning margin in 159 seats. Labour came second in as many of these seats as the Conservatives. In Scotland, Labour voters switching to the SNP cost it 40 seats—but some Corbyn advocates have argued that even these gains would be dwarfed if Labour could mobilise more of Britain’s 16m non-voters.

On the one hand some of those things most strongly associated with voting Labour are the same things associated with people not voting at all: being young, having low levels of educational attainment and being unemployed. Labour performs better in those constituencies where more of these types of people are present and turnout is correspondingly lower. This is brought home starkly when you plot on a seat-by-seat basis the relationship between the proportion of Labour voters and non-voters on the one hand and levels of spending on working age benefits on the other. The key question is whether getting more of these non-voters to vote Labour would gain it enough seats or, more likely, pile up support in those areas where it is already dominant—it holds 60 per cent of all the seats in Parliament with below average turnouts.

Perhaps it’s better to look at the people who actually voted in May 2015. This suggests that Labour’s problem lies less in failing to energise those who were alienated from voting in 2015 and more with actual…

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