It is a political call.  The caller wants to ask you questions about a particular candidate or persuade you to vote a particular way.

These type of political calls start to come in on every two and four year cycles.  This cycle is going to be bad since there are so many candidates running for president.

Unfortunately there is little you can do to stop them as they have excluded themselves from the do not call rules.

If you have the means to do so, you can do what I have done and dedicate a computer and create your own PBX style phone system to intercept these type of calls.