  We describe a consistent approach to factorization of scattering amplitudes
for exclusive processes beyond the leading twist approximation. The method
involves the Taylor expansion of the scattering amplitude in the momentum space
around the dominant light-cone direction and thus naturally introduces an
appropriate set of non-perturbative correlators which encode effects not only
of the lowest but also of the higher Fock states of the produced particle. The
reduction of original set of correlators to a set of independent ones is
achieved with the help of equations of motion and invariance of the scattering
amplitude under rotation on the light-cone. We compare the proposed method with
the covariant method formulated in the coordinate space, based on the operator
product expansion. We prove the equivalence of two proposed parametrizations of
the rhoT distribution amplitudes. As a concrete application, we compute the
expressions of the impact factor for the transition of virtual photon to
transversally polarised rho-meson up to the twist 3 accuracy within these two
quite differents methods and show that they are identical.
