We provide an example for the use of a generalized potential functional in a nonequilibrium pattern forming process by re-examining the critical behavior of the normal rolls in an electrically-driven nematic cell. We show that the viscous torque due to the flow on the director can be derived from a functional and consequently convert the equation of state to a gradient form. The standard hydrodynamic together with Maxwell’s equations are used to determine an explicit form of the field variables. First order nonlinear corrections to the linear solutions are obtained using a technique similar to the E-expansions. Upon minimization of the nonequilibrium potential with respect to the state parameters, we construct a bifurcation diagram for a continuous transtition and reproduce the observed epsilon(1/2) power-law dependence. A criterion for the formation of the normal rolls via a discontinuous transition is also given within the model.