  The sensitivity of transport in CMR manganite to external fields is examined
using a PZT-based field effect configuration with a La0.7Ca0.3MnO3 channel
subjected to electric and magnetic fields, separately and in conjugation. We
not only find a colossal electroresistance (CER) of ~76% at 4X10^5 V/cm, but
also a remarkable complimentarity of this CER with the widely studied CMR.
Specifically, the ERmax (MRmax) of the system is largely independent of the
magnetic (electric) field biasing, and for equal conductivity values, the ER
(MR) is lower (higher) for T<Tp than that for T>Tp. The size and systematics of
the effect strongly favor a percolative phase separation picture.
