  The effective potential of the order parameter for confinement is calculated
within the Hamiltonian approach by compactifying one spatial dimension and
using a background gauge fixing. Neglecting the ghost and using the
perturbative gluon energy one recovers the Weiss potential. From the full
non-perturbative potential calculated within a variational approach a critical
temperature of the deconfinement phase transition of 269 MeV is found for the
gauge group SU(2).
