  We adapt the conjectural local Langlands parameterization to split
metaplectic groups over local fields. When $\tilde G$ is a central extension of
a split connected reductive group over a local field (arising from the
framework of Brylinski and Deligne), we construct a dual group $\mathbf{\tilde
G}^\vee$ and an L-group ${}^L \mathbf{\tilde G}^\vee$ as group schemes over
${\mathbb Z}$. Such a construction leads to a definition of Weil-Deligne
parameters (Langlands parameters) with values in this L-group, and to a
conjectural parameterization of the irreducible genuine representations of
$\tilde G$. This conjectural parameterization is compatible with what is known
about metaplectic tori, Iwahori-Hecke algebra isomorphisms between metaplectic
and linear groups, and classical theta correspondences between $Mp_{2n}$ and
special orthogonal groups.
