I agree with Tom, there are plenty of democrats who won't support this legislation along with plenty of republicans who will. It isn't a Republican vs Democrat issue.
I'll have to find the article again, but the real issue seems to be the doping of america's children. By that, I'm talking about the so called mood modifiers that are getting prescribed to children at a young age. Instead of recognizing and dealing with children's problems and teaching them how to cope, the schools and doctors are instead doping them up to mask the issues. If memory serves and the article was right, all of these mass school shooting have been committed by people who were doped up early in life to deal with "issues" instead of being taught how to cope with every day life.
Long story short, it's a society problem of masking mental health issues instead of fixing them. Not a gun control issue