Radar-based microwave imaging has been proposed as a complementary modality for early stage breast cancer screening. A considerable challenge for the successful implementation of this technique is the reduction of clutter, or components of the signal originating from objects other than the tumor. To remedy problems that arise due to the breast shape, size and tissue variations, a novel technique is presented that identifies and localizes the source of a target response. The ability of the algorithm to predict the time-of-arrival of a tumor response in a signal corrupted by clutter is demonstrated.