Answer:
Whip
Step-by-step explanation:
A Whip in the United States Congress is an official in the congress whose main duty is to make sure that each member of the congress, the Senates and the member of representatives, vote according to the ideology or framework of their respective political party and not by their individual ideology and judgement.
The party member should vote in accordance to their party platform. They work closely with the rank and file members of the party.
Thus the answer is "Whip".