  Within the context of an extended Nambu - Jona-Lasinio model, we analyze the
role of the axial-vector $a_1(1260)$ and $a_1(1640)$ mesons in the decay
$\tau\to\nu_\tau \rho^0\pi^-$. The contributions of pseudoscalar $\pi$ and $\pi
(1300)$ states are also considered. The form factors for the decay amplitude
are determined in terms of the masses and widths of these states. To describe
the radial excited states $\pi (1300)$ and $a_1(1640)$ we introduce two
additional parameters which can be estimated theoretically, or fixed from
experiment. The decay rate and $\rho\pi$ mass spectrum are calculated.
