We define as populist a party that champions short-term protection policies without regard for their long-term costs. First, we study the demand for populism: we analyze the drivers of the populist vote using individual level data from multiple waves of surveys in Europe. Individual voting preferences are influenced directly by different measures of economic insecurity and by the decline in trust in traditional parties.However, economic shocks that undermine voters' security and trust in parties also discourage voter turnout, thus mitigating the estimated demand of populism when ignoring this turnout selection. Economic insecurity affects intentions to vote for populist parties and turnout incentives also indirectly because it causes trust in parties to fall. Second, we study the supply side: we find that populist parties are more likely to appear when the drivers of demand for populism accumulate, and more so in countries with weak checks and balances and with higher political fragmentation.The non-populist parties' policy response is to reduce the distance of their platform from that of new populist entrants, thereby magnifying the aggregate supply of populist policies.

We compare turnout under proportional power‐sharing electoral systems and winner‐take‐all elections. The effect of such institutional differences on turnout depends on the distribution of voter preferences. If the two parties have relatively equal support, turnout is higher in a winner‐take‐all system; the result is reversed when there is a clear underdog. We report findings from a laboratory experiment that was designed and conducted to explore this theoretical hypothesis and several other secondary hypotheses that are also implied by the theoretical model. The results are broadly supportive of the theoretical predictions on comparative turnout, the partial underdog compensation effect and the competition effect.

SUMMARY Populist parties are likely to gain consensus when mainstream parties and status quo institutions fail to manage the shocks faced by their economies. Institutional constraints, which limit the possible actions in the face of shocks, result in poorer performance and frustration among voters who turn to populist movements. We rely on this logic to explain the different support of populist parties among European countries in response to the globalization shock and to the 2008–11 financial and sovereign debt crisis. We predict a greater success of populist parties in response to these shocks in Eurozone (EZ) countries, and our empirical analysis confirms this prediction. This is consistent with voters’ frustration for the greater inability of the EZ governments to react to difficult-to-manage globalization shocks and financial crises. Our evidence has implications for the speed of construction of political unions. A slow, staged process of political unification can expose the European Union to a risk of political backlash if hard to manage shocks hit the economies during the integration process.