they talk about gun rights, what about chris right to live? reporter: what was it that drove to you do that? it wasn t a very rational decision. i have to tell you. i just did it. i can t accept the way he died. it was preventible. and it s going on every single day in this country. too many have died! we should say to ourselves, not one more. reporter: an impassioned plea becomes a rallying cry at the university s memorial. not one more! reporter: not one more backs a hash tag. and then 2.4 million postcards then this grieving father with every time for gun safety delivering them to lawmakers across the country. 60,000 to marco rubio in florida. i delivered postcards to the governor of pennsylvania. reporter: five states and still counting. he quits his job, successfully