Sunday's presidential runoff in Costa Rica pits a conservative evangelical singer against a former cabinet minister from the ruling center-left Citizens’ Action Party, and has been fought largely over gay marriage.

Why it matters: Costa Rica is Latin America's oldest democracy, but crime, high unemployment and corruption allegations have jolted the country's historically stable politics. The gay marriage debate has added fuel to the fire. Per the Economist, "dissatisfaction is showing up as support for unconventional candidates."