  Elastic diffractive scattering of nucleons is described in terms of
Regge-eikonal approach. It is demonstrated that, in a wide kinematic region
(starting from the U-70 energies), the eikonal of proton-proton scattering can
be approximated by the sum of two Reggeon exchange terms (namely, the so-called
soft Pomeron and $f$-Reggeon contributions). The range of applicability of the
considered approximation is determined. The predictive value of the proposed
phenomenological scheme is verified.
