to cause a persuasive movement in any large body of influence, i.e., a mass of people, through means by which a lesser influence is utilized.
From the phrase, 'It's the tail that wags the dog.' This can be seen when a dog begins to wag it's tail, and it's body then follows.
in partisan politics, an unpopular party will wag the dog using a variety of provocative political manoeverings and machinations to undermine the public favour from the popular party, out of which a momentum can be borne.