Espionage to separate foe from friend

A leading politician has deployed several moles from among his loyalists to spot the party stalwarts hostile to him despite being cordial for all appearances. The leader has resorted to this move, following intelligence that a section of the front-liners is ill-disposed towards him. 

Whenever, several party members meet in the lobby or elsewhere either by accident or design or are at a private discussion, these moles would join them under some pretext, they say.