Spin transport in organic semiconductors has garnered increased interest in the last decade due in part to the large room temperature organic magnetoresistance (OMAR) effect. This effect originates from the nuclear interactions with bottlenecked carrier spin pairs which are suppressed by applied fields. In this article the authors describe a new regime for low-field magnetoresistance in organic semiconductors, in which the spin-relaxing effects of localized nuclear spins and electronic spins interfere. In addition to elucidating the fundamental mechanisms of OMAR, this result has implications for improving the design of organic-based devices.