  We derive the requirements that a generic axion-like field has to satisfy in
order to play the role of the inflaton field in the warm inflation scenario.
Compared to the parameter space in ordinary natural inflation models, we find
that the parameter space in our model is enlarged. In particular, we avoid the
problem of having an axion decay constant $f$ that relates to the Planck scale,
which is instead present in the ordinary natural inflation models; in fact, our
model can easily accommodate values of the axion decay constant that lie well
below the Planck scale.
