  The elliptic flow in heavy ion collisions at RHIC is studied in a multiphase
transport model. By converting the strings in the high energy density regions
into partons, we find that the final elliptic flow is sensitive to the parton
scattering cross section. To reproduce the large elliptic flow observed in
Au+Au collisions at $\sqrt s=130A$ GeV requires a parton scattering cross
section of about 6 mb. We also study the dependence of the elliptic flow on the
particle multiplicity, transverse momentum, and particle mass.
