We study two districts’ voluntary co-financing of a centrally provided public good, e.g., transport infrastructure. Outcomes are compared to a surplus-maximizing level of public good provision. We show that both co-financing and lobbying raise the amount of public good provided. Co-financing and lobbying are substitutes. Co-financing (or co-financing combined with lobbying) raises the provision of the public good to a higher level than lobbying alone. Co-financing can thus reduce rent-seeking. Finally, we show that under uncertainty about district type (high or low benefit), co-financing combined with lobbying can be used to find and retain a separating equilibrium.