In the Senate - which currently has 54 Republicans and 46 Democrats (or Democratic-supporting independents) - the individual state populations are the key. The votes of Senators John Barrasso and Mike Enzi in pro-gun Wyoming (population 584,153) have the same weight as gun-control-backing Senators Dianne Feinstein and Barbara Boxer in California (population 38.8 million).
And when it comes to the most divisive proposal queried in the Pew poll - a ban on assault weapons that is supported by 70% of Democrats but only 48% of Republicans - just seven states, including California, have enacted similar measures for their jurisdictions. The large majorities backing gun control in Illinois, for instance, are more than outweighed by pro-gun states like Alaska, Nebraska and Alabama, with a fraction of its population.