  We re-examine the possible magnitude of the supersymmetric contribution to
$R_b$ with imposed all available phenomenological constraints and demanding
good quality of the global fit to the precision electroweak data. For low
$\tan\beta$ we find a new region of the parameter space, with $M_2\approx
|\mu|$ and $\mu<0$ where $R_b$ remains large, $\sim0.2180$ even for the lighter
chargino as heavy as $90-100$ GeV. It is an interesting mixture of the
up-higgsino and gaugino. The r\^ole of various phenomenological constraints is
discussed in analitic form and importance of small but non-negligible
left-right mixing in the stop sector is emphasized in this context. The large
$\tan\beta$ option for enhancement of $R_b$ is also reviewed. The available
data do not rule out this scenario.
