Immediately return all campaign contributions from the NRA or other gun lobbying groups.

By one count, 355 mass shootings (with 4 or more dead) have occurred in the U.S. this year. That comes to more than one every day. The Law Center to Prevent Gun Violence estimates more than 100,000 Americans are victims of gun violence every year.

According to polls, most Americans agree that guns -- particularly assault weapons like those used in San Bernardino on Wednesday -- are too easily accessible. No gun control could completely prevent mass shootings, but today’s gun laws ease the path to such tragedies.

Too many of our senators and representatives pay more attention to the financial muscle of the gun lobby than to the daily slaughter of innocent fellow citizens and the clear wishes of their constituents.

Last year alone, the National Rifle Association invested $28 million in “independent expenditures” aimed at supporting some candidates and defeating others.

The gun lobby backs these political contributions with outlays to influence those in office. Since 2000, pro-gun groups have spent more than $101 million in lobbying on Capitol Hill.

The pro-gun forces are so strong that in 1996 they persuaded Congress to ban federal funding of research into the causes of gun violence.

That ban remains. America funds research aimed at finding ways to limit the damage done by all sorts of other dangerous products, from automobiles to toys, but not a penny goes to study the public health dangers posed by the 300 million-plus firearms in circulation.

How much more must the nation endure before Congress rouses itself?