Expanding some background checks is under consideration in Congress as lawmakers respond to public and political pressure for stricter laws following December's shooting massacre at a Connecticut elementary school.

Possible steps include better monitoring of people with mental illness to prevent them from obtaining firearms.

Mayors Against Illegal Guns aired an ad during the Super Bowl advocating universal background checks for gun sales.

President Barack Obama also reiterated his call on Monday for comprehensive steps to address gun violence, including expanded background checks.