The formalism i s given for a partial-wave analysis of a low-mass two-body subsystem produced via a double-Regge amplitude at small momentum transfer. This method i s applied to the Reggeized Deck amplitude for the reaction TN-paN in the p-a mass region of the A enhancement. At lower mass values the results a r e less sensitive to the exact form of the pion Regge trajectory, and about 7 5 4 0 % of the cross section in the A* region i s given by a 1+ Swave p-n state. This amplitude i s largely real and the Argand diagrams for the partial waves do not show resonant structure. However, phenomenologically it i s difficult to distinguish between the Berger amplitude and an A i-resonance production amplitude. The spin-parity decomposition in the A2 mass region i s also discussed.