"Cantamañanas" = Morningsinger*

Informal and irresponsible person who is not worth either respect or credit. To be all talk and no action.
It's been quite interesting to google "cantamañanas" in images as many of the pictures directed me to policitians, erm... why would that be so? ;)
"Menudo tipo. Es un cantamañanas"
"¿Cómo se les ocurre darle un puesto de responsabilidad a ese cantamañanas?"
"La empresa la dirigen cuatro cantamañanas"