john, diana. the magnitude of this tragedy is so enormous, investigators are still compiling thousands of pages and interviews about what happened. but today is about remembering the victims. >> allison wyatt, age 6. >> reporter: six months later, the loss is still incomprehensible. >> gracie mcdonald, age 7. >> reporter: 20 first graders, 6 educators murdered at sandy hook elementary. the families of the victims are now fighting against fading memories. they're using the anniversary to renew a push for new gun control laws. >> we're not going away. this heartbreak that i carry, this life sentence that i have, no one should ever bear this burden. >> reporter: the families' emotional pleas have been unable to move congress. a senate bill to expand background checks stalled earlier this year. proposed bans on assault-style weapons and high-capacity clips are off the table. >> our hearts are broken. our spirit is not. >> reporter: top lawmakers say they are gearing up for another push to expand background checks. the group mayors against illegal guns, today joins the campaign with this bus, painted with the names of victims of gun violence. still, opposition remains strong. the road ahe