(Politico) The Senate voted down a gun control measure last month, but the fight is just beginning.

The National Rifle Association and new pro-gun control groups headed by former Rep. Gabby Giffords and Michael Bloomberg are in an arms race since a background check bill narrowly failed in the Senate last month – ramping up their fundraising, airing attack ads and revving up their grassroots machines.

There was a time when a failed gun bill might have quietly slipped off the stage. But the dynamics have shifted, since the NRA is no longer the only group in the gun debate with money, power and some signs of staying power.

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