The process by which campaigners learn which issues matter to potential voters and which candidates these voters prefer by conducting interviews on the telephone or in person is called a (n)

Answer: Canvassing

Explanation:

To canvas means to tally for votes in an election, it's a scenario where the candidate seeks to find how he can convince the audience or society to vote for him or her. This is been done by rally, community services, approaching towns and villages for seminar.