A simple scheme using a single-ion approach has been developed to calculate the pseudopotential and pair potential for aluminum. The electron density around an isolated Al nucleus in a homogeneous electron gas is calculated self-consistently using the density-functional method. The induced charge density is then used to produce an ab initio local pseudopotential and the interionic potential. Two different schemes for embedding the Al nucleus into the jellium have been considered. A model where the Al nucleus is in the jellium vacancy gives better pseudo- and pair potentials than the model where the Al nucleus is embedded into a completely homogeneous electron gas. Using the resulting potentials, the cohesion energy, equilibrium lattice constant, bulk modulus, vacancy formation energy, and the resistivity of the liquid phase were calculated. The sensitivity of the results to various approximations in the model, the volume dependence of the pair potential, and the effects of the ionic core are discussed.