  We study numerically the dependence of the difference between the
longitudinal and transverse gluon propagators, $\Delta=D_L-D_T$, on the
momentum and temperature at $T\gtrsim T_c$ both in SU(2) and SU(3)
gluodynamics. It is found that the integral of $\Delta$ with respect to the
3-momentum is sensitive only to infrared dynamics and shows a substantial
correlation with the Polyakov loop. At $T=T_p\sim 1.2 T_c$ it changes sign
giving some evidence that $T_p$ can serve as a boundary of the postconfinement
domain.
