Suppose there are two vice presidents vying for influence/supremacy within an organization.
One vice president is admittedly weaker than the other, so he forms an alliance with a powerful underling who can tip the balance and make him (his team) the stronger.
Is there a word for this third person, the underling on Team B, whose involvement would tip the balance?
I'm thinking of a politically-charged word like "power-broker", but in a more subservient role. (Power brokers pull the marionette strings, whereas this fellow is talent.)
Note: I would create the tag "mot-juste" but I presently lack the required rep.