A number of developing country governments have introduced ambitious anti-poverty programs in recent years, but the dynamic effects of these initiatives on governments' election performance remain poorly understood. Especially in contexts with low program implementation quality, public support for government interventions may be high initially but decline over time as citizens observe the actual program benefits. This paper analyzes the election impacts of the largest public-works program in the world, the Indian NREGS. Using a regression-discontinuity framework, the results suggest that length of program exposure and implementation quality matter: voter support in low implementation quality areas declines with longer program access. This effect is muted in well-implemented areas, where voter turnout is higher and incumbents of any party affiliation also benefit. The government payoff from implementing a large anti-poverty program may therefore be short-lived unless implementation challenges are resolved.