ein Wörtchen mitzureden haben
to have a say in a matter; to have the right to help decide
Origin
No separate historical origin is documented (origin uncertain). The diminutive 'Wörtchen' deliberately understates: it is only a 'little word', yet one that carries weight in the decision. (Distinct from 'ein Wörtchen mit jemandem zu reden haben' = to take someone to task.)
Building blocks
Words in this expression
Examples
Bei möchte ich auch ein Wörtchen mitzureden haben.
I'd like to have a say in this decision too.