going to tell you what we're going to do. >> reporter: under pressure from an emotional and grieving audience, florida senator marco rubio showed new openness to a number of more restrictive gun measures. breaking with the nra. the organization that has given him an a-plus top rating and some members of his own party. rubio now says he supports raising the minimum age for raising a rifle from 18 to 21. >> i absolutely believe that in this country, if you are 18 years of age, you should not be able to buy a rifle and i will support a law that takes that right away. >> reporter: a dramatic change from his initial reaction in the aftermath of the parkland shooting. on the senate floor last week, one day after the shooting, rubio didn't have any specific answers. >> if we do something, it should be something that works. and the struggle up to this point has been that most of the proposals that have been offered would not have prevented, not just yesterday's tragedy, but