The nonlinear filamentation in a nonrelativistic collisional current-carrying plasma in the diffusion frequency region is investigated. It is shown that by using the two-fluid plasma equations and Ampere's law and assuming that the plasma is nonisothermal and inhomogeneous, the spatial evolution of the magnetic field in a plasma is described by the Lienard nonlinear differential equation. Also, it is shown that a transverse filamentation and density steepening can occur in the static limit. Furthermore, the profiles of magnetic field and the electron density variation have a nonsinusoidal shape in the nonlinear regime. Moreover it is shown that the shape of the transverse filamentation varies due to the nonlinear effect in the static limit.