The paper analyzes how the equilibrium electoral policy platforms change in a probabilistic model of electoral competition between two purely opportunistic and corrupt candidates in the presence of exogenously given interest groups. The economic policy of interest in this model is the tax to fund the public good provision. We derive equilibrium tax platforms for three different specications of the model: benchmark (no swing voters and no lobbies), pure-swing and swing-voter plus interest groups. It is found that the equilibrium tax platform of an electoral candidate under benchmark scenario is greater than or equal to the same under the pure swing voter case because the presence of swing-voters in the economy dilutes the intensity of economic policy preferences of each group and therefore the choice of (tax) policy. Furthermore, it is found that, an increase in the honesty parameter of the candidate results in greater donations by the interest group towards that candidate. Additionally, two signicant effects have been found to be at work in driving the comparative statics results, namely the relative swing voter effect and the relative organizational strength of lobbies effect. Based on which of these two effects is stronger, we find that the equilibrium policy platforms of candidates (tax platform) sway in favour of the more dominant voter group.