Single-Issue Campaigns and Multidimensional Politics
In most elections, voters care about several issues, but candidates may have to choose only a few to build their campaign on. The information that voters will get about the politician depends on this choice, and it is therefore a strategic one. In this paper, I study a model of elections where voters care about the candidates' competences (or positions) over two issues, e.g., economy and foreign policy, but each candidate may only credibly signal his competence or announce his position on at most one issue. Voters are assumed to get (weakly) better information if the candidates campaign on the same issue rather than on different ones. I show that the first mover will, in equilibrium, set the agenda for both himself and the opponent if campaigning on a different issue is uninformative, but otherwise the other candidate may actually be more likely to choose the other issue. The social (voters') welfare is a non-monotone function of the informativeness of different-issue campaigns, but in any case the voters are better off if candidates are free to pick an issue rather than if an issue is set by exogenous events or by voters. If the first mover is able to reconsider his choice in case the follower picked a different issue, then politicians who are very competent on both issues will switch. If voters have superior information on a politician's credentials on one of the issues, this politician is more likely to campaign on another issue. If voters care about one issue more than the other, the politicians are more likely to campaign on the more important issue. If politicians are able to advertise on both issues, at a cost, then the most competent and well-rounded will do so. This possibility makes voters better informed and better off, but has an ambiguous effect on politicians' utility. The model and the results may help understand endogenous selection of issues in political campaigns and the dynamics of these decisions.
I am grateful to Daron Acemoglu, Attila Ambrus, David Austen-Smith, V. Bhaskar, Colin Camerer, Faruk Gul, Matthew Jackson, Patrick Le Bihan, César Martinelli, Joseph McMurray, Mattias Polborn, Maria Socorro Puy, Larry Samuelson, Andrzej Skrzypacz, Konstantin Sonin, and participants of the PECA 2012 conference, NES 20th Anniversary conference, the Econometric Society meeting in Los Angeles in 2013, Wallis 2013 Conference in Rochester, Political Institutions Conference in Montreal, ASSA 2015 conference in Boston, MPSA 2015 conference in Chicago, and seminars at the University of British Columbia, University College London, Duke University, MIT, New York University, Northwestern University, University of Pennsylvania, and Queen's University at Belfast for valuable comments and to Ricardo Pique and Christopher Romeo for excellent research assistance. The views expressed herein are those of the author and do not necessarily reflect the views of the National Bureau of Economic Research.