Stability of the Chari-Loktev bases for local Weyl modules of ${\mathfrak{s}\mathfrak{l}}_{r+1}[t]$

We prove stability of the Chari-Loktev bases with respect to the inclusions of local Weyl modules of the current algebra ${\mathfrak{s}\mathfrak{l}}_{r+1}[t]$. This is conjectured in \cite{RRV2} and the $r=1$ case is proved in \cite{RRV1}. Local Weyl modules being known to be Demazure submodules in the level one representations of the affine Lie algebra $\widehat{{\mathfrak{s}\mathfrak{l}}_{r+1}}$, we obtain, by passage to the direct limit, bases for the level one representations themselves.