When then-Senator and Democratic frontrunner Barack Obama was caught on tape musing about “bitter” Americans who “cling to guns or religion” in 2008, his opponent, Hillary Clinton, seized on the chance to turn the episode into a springboard for a comeback. Appealing to rural Democrats, she talked up her own enjoyment of shooting with her dad and rescinded her previous calls for a national gun registry. After that effort to use guns as a voting wedge fell short, top Democrats had little interest in discussing gun policy, beyond loosening a few niche gun restrictions.

Just as Obama was sewing up the Democratic nomination, the Supreme Court was preparing to deliver gun reformers a stinging blow with its historic Heller v. District of Columbia decision, in which the justices upended centuries of precedent and declared that the Constitution does indeed guarantee the individual right to bear arms. The decision demoralized advocates already sidelined by their putative political allies.

Eight years later, cheering a House occupation broadcast by a new technology, sustained by pizza delivered by new pro-gun reform groups, and fired up by a voter calculus that has them believing they can win on the gun issue, Democrats have taken on the issue with a gusto that would have been impossible to imagine at the start of Obama’s presidency. Prospects for the bills that the party has been fiercely pushing in Washington are unclear, but this much seems certain: Whatever happens on Capitol Hill, a huge test has been set for November.

Here’s how the current showdown was put in motion, in 16 specific steps.