  Simultaneous $\chi^{2}$ analyses previously made for elastic scattering and
fusion cross section data for the $^{6}$Li+$^{208}$Pb system is extended to the
$^{7}$Li+$^{208}$Pb system at near-Coulomb-barrier energies based on the
extended optical model approach, in which the polarization potential is
decomposed into direct reaction (DR) and fusion parts. Use is made of the
double folding potential as a bare potential. It is found that the experimental
elastic scattering and fusion data are well reproduced without introducing any
normalization factor for the double folding potential and that both the DR and
fusion parts of the polarization potential determined from the $\chi^{2}$
analyses satisfy separately the dispersion relation. Further, we find that the
real part of the fusion portion of the polarization potential is attractive
while that of the DR part is repulsive except at energies far below the Coulomb
barrier energy. A comparison is made of the present results with those obtained
from the Continuum Discretized Coupled Channel (CDCC) calculations and a
previous study based on the conventional optical model with a double folding
potential. We also compare the present results for the $^7$Li+$^{208}$Pb system
with the analysis previously made for the $^{6}$Li+$^{208}$Pb system.
