CNN:

Next time there's a mass shooting, don't jump to blame the National Rifle Association and lax gun laws. Look first at the shooter and the mental health services he did or didn't get, and the commitment laws in the state where the shooting took place.
Strengthening gun control won't stop the next mass shooter, but changing our attitudes, the treatment options we offer and the laws for holding the mentally unstable and mentally ill for treatment just might.

This is the next line of defense for the NRA (the first being the entertainment industry): Mental illness and not easy access to guns is what's really going on. But this position is not as clean and stable as the first one—the one that blames video games and Hollywood's liberals. The problem with it can be found in the second paragraph of this post "Ronald Reagan’s shameful legacy: Violence, the homeless, mental illness," which is an excerpt from the book American Psychosis: How the Federal Government Destroyed the Mental Illness Treatment System:

One month prior to the [presidential election of 1980], President Carter had signed the Mental Health Systems Act, which had proposed to continue the federal community mental health centers program, although with some additional state involvement. Consistent with the report of the Carter Commission, the act also included a provision for federal grants “for projects for the prevention of mental illness and the promotion of positive mental health,” an indication of how little learning had taken place among the Carter Commission members and professionals at NIMH. With President Reagan and the Republicans taking over, the Mental Health Systems Act was discarded before the ink had dried and the CMHC funds were simply block granted to the states. The CMHC program had not only died but been buried as well. An autopsy could have listed the cause of death as naiveté complicated by grandiosity.

A big part of the Reagan revolution was about kicking mentally ill people out of hospitals (socialism) and on to the streets (individualism). As a consequence, those who take mental illness seriously, are also taking a political position that is held predominately by the Left. That position says: Mental illness is not about the individual but about society providing adequate support and services to those who suffer from this real form of illness. The author, Mel Robbins, of the CNN opinion piece claims that the NRA, an organization that's far on the Right, does take this issue seriously, does see mental illness in a way that is consonant with the Left. But is that really possible? Is this where the NRA wants to be? Siding with a kind of politics that has the strengthening of gun control laws as one of its core agendas? For sure, the NRA would much prefer to stick with the first line of defense.