  We have studied the effects of band filling and bandwidth control on the
chemical potential in perovskite manganites $R_{1-x}A_x$MnO$_3$ ($R$ : rare
earth, $A$ : alkaline earth) by measurements of core-level photoemission
spectra. A suppression of the doping-dependent chemical potential shift was
observed in and around the CE-type charge-ordered composition range, indicating
that there is charge self-organization such as stripe formation or its
fluctuations. As a function of bandwidth, we observed a downward chemical
potential shift with increasing bandwidth due to the reduction of the
orthorhombic distortion. After subtracting the latter contribution, we found an
upward chemical potential shift in the ferromagnetic metallic region
$0.3<x<0.5$, which we attribute to the enhancement of double-exchange
interaction involving the Jahn-Teller-split $e_g$ band.
