Yes, they do, but only by forming an opinion and later act on it you can tip the balace one way or another. For example, if lots of people complain about the general inadequacy of death penalty, chances are that some people in the US who supports death penalty end up questioning it, I supose. While if we all turn to the other side things may remain the same.
I'm against death penalty, specially as most people who get death penalty in the US belongs to the so called minorities, and unfortunately many have not received a fair trial. In this particular case I would bet the father (hispanic) would be sent to the row while the mother may not.