  The effective action with homogeneous valence (off-diagonal) gluons as
background fields in the extended SU(2) model of QCD is obtained in one-loop
approximation. We keep the manifest gauge and Lorentz invariance during whole
calculation by using a special gauge-fixing recipe and taking into account the
quartic interaction terms in the original Lagrangian as well. It has been shown
that the effective Lagrangian gains a positive imaginary part.
