Two types of cluster–cluster potentials are obtained for the lithium nuclei. The first is an attractive one and the second is a superposition of repulsive and attractive Gaussian forces. The ground-state wave functions of the lithium nuclei 6 Li , 7 Li , 8 Li , and 9 Li are expanded in terms of products of two wave functions: the first represents the set of A-4 nucleons and the second represents the set of the last four nucleons. In the construction of these wave functions, we have used the basis functions of the translation-invariant shell model. The expansion coefficients of the factorizations of these wave functions are products of four-particle orbital and spin-isospin fractional parentage coefficients. Two least-square formulas for the cluster–cluster potentials, which depend on the mass number A, are fitted for the lithium nuclei.