Recent results on the maximization of the charged-particle action I x0,x1 in a globally hyperbolic spacetime are discussed and generalized. We focus on the maximization of I x0,x1 over a given causal homotopy class C of curves connecting two causally related events x 0 ≤ x 1 . Action I x0,x1 is proved to admit a maximum on C, and also one in the adherence of each timelike homotopy class C. Moreover, the maximum σ 0 on C is timelike if C contains a timelike curve (and the degree of differentiability of all the elements is at least C 2 ). In particular, this last result yields a complete Avez-Seifert type solution to the problem of connectedness through trajectories of charged particles in a globally hyperbolic spacetime endowed with an exact electromagnetic field: fixed any charge-to-mass ratio q/m, any two chronologically related events x 0 ≪ x 1 can be connected by means of a timelike solution of the Lorentz force equation (LFE) corresponding to q/m. The accuracy of the approach is stressed by many examples, including an explicit counterexample (valid for all q/m) in the nonexact case.As a relevant previous step, new properties of the causal path space, causal homotopy classes and cut points on lightlike geodesics are studied.