Background checks are widely considered the heart of the gun control drive.

NPR: Both Sides Hunt Support In Background Check Fight

Expanded background checks are the core of the Democratic gun control drive.

NPR: Senate Ready To Launch Gun Control Debate

All three helped drive new gun control measures in New York, Colorado and in Connecticut, where Gov. Dannel P.

WSJ: Few states find narrow route to gun control laws

And in Arizona, a staunchly pro-gun state where the 2011 assassination attempt of Rep. Gabrielle Giffords in Tucson left six dead and 13 wounded, the drive for gun control following Newtown has been a non-starter.

WSJ: Few states find narrow route to gun control laws