  The conductance of a weakly interacting electron gas in the presense of a
single scatterer is found at arbitrary strength of the scattering potential. At
weak interaction, a simple renormalization group approach can be used instead
of the standard bosonization procedure. Our technique allows to take into
account the {\em backscattering\/} of electrons that leads to a
non-Luttinger-liquid behavior of the low-temperature conductance. In the
presence of magnetic field, the backscattering may give rise to a peak in
differential conductance at bias equal to the Zeeman energy.
