  As a first step to analyze the electromagnetic meson production reactions in
the nucleon resonance region, the parameters of the hadronic interactions of a
dynamical coupled-channel model, developed in {\it Physics Reports 439, 193
(2007)}, are determined by fitting the $\pi N$ scattering data. The channels
included in the calculations are $\pi N$, $\eta N$ and $\pi\pi N$ which has
$\pi\Delta$, $\rho N$, and $\sigma N$ resonant components. The non-resonant
meson-baryon interactions of the model are derived from a set of Lagrangians by
using a unitary transformation method. One or two bare excited nucleon states
in each of $S$, $P$, $D$, and $F$ partial waves are included to generate the
resonant amplitudes in the fits. The parameters of the model are first
determined by fitting as much as possible the empirical $\pi N$ elastic
scattering amplitudes of SAID up to 2 GeV. We then refine and confirm the
resulting parameters by directly comparing the predicted differential cross
section and target polarization asymmetry with the original data of the elastic
$\pi^{\pm} p \to \pi^{\pm} p$ and charge-exchange $\pi^- p \to \pi^0 n$
processes. The predicted total cross sections of $\pi N$ reactions and $\pi
N\to \eta N$ reactions are also in good agreement with the data. Applications
of the constructed model in analyzing the electromagnetic meson production data
as well as the future developments are discussed.
