chief whipnoun [ C usually singular ]
also Chief Whip uk/ˌtʃiːf ˈwɪp//ˌtʃiːf ˈwɪp/in many elected political systems, a member of a political party in a parliament, etc. who is in charge of making certain that other party members are present at voting time and that they vote in a particular way. In the British political system, the chief whip of the governing political party in parliament is also a member of the cabinet (= group of important government ministers) and has the position of Parliamentary Secretary to the Treasury:
Castagnetti was chief whip of the Italian centre-left Margherita party.
They walked the few yards back to the Chief Whip's office in Downing Street.