Can parties recruit postal voters? Experimental evidence from Britain

While easily-accessible postal voting is on the rise in many countries, the implications for electoral campaigns are largely under-researched. Indeed, parties actively try to sign supporters up to postal votes to make it easier for them to turn out. But how effective are these efforts to recruit supporters on to postal votes? We present an original, pre-registered postal voter recruitment experiment – the first conducted outside the US – completed during the May 2018 UK elections. We test the effect of a common recruitment tactic – letters and application forms sent to supporters. Despite being widely used by parties, we find that these efforts are ineffective at both recruiting and mobilising supporters. While the rewards of successfully signing supporters up to postal voting are potentially substantial, our results suggest that parties should consider the most effective ways of doing so.