Peter Ambler is the executive director of Giffords , an organization founded by former US Rep. Gabrielle Giffords and former NASA astronaut and retired Navy Capt. Mark Kelly to fight gun violence. Ambler has worked for Democrats in Congress and on campaign staffs. The views expressed in this commentary are his own. View more opinion articles on CNN.

(CNN) Nearly a decade ago, Barack Obama and large Democratic majorities in Congress demonstrated one of the most prolific records of legislating in the history of the republic. As a congressional staffer at the time, I would have never guessed that where they failed -- in any effort to take on the National Rifle Association and pass gun safety legislation -- a new generation of freshmen members of Congress would succeed. But this month, that's exactly what we're witnessing .

Tragically, the cost to American families and communities while we waited for this progress has been far too high. The vote by the House to approve the Bipartisan Background Checks Act comes just over one year after the tragic shooting at Marjory Stoneman Douglas High School in Florida and six years after the Sandy Hook massacre in Connecticut.

It comes eight years after my boss, former US Rep. Gabby Giffords, was shot in the head outside a Tucson grocery store.

This vote is the first meaningful response by the new Democratic majority to an epidemic that cost nearly 40,000 American lives just in the first year of Donald Trump's presidency, according to the Centers for Disease Control and Prevention.

It's also the latest proof point of a tectonic shift in the politics of an issue that has for so many years vexed those in search of solutions.

This didn't happen by accident. Previously, arguments for gun safety laws got lost in the minutiae of policy. Today, we've worked to make gun reform a kitchen table issue

I've worked as a gun safety advocate for more than six years, and I'm the father of a 2-year-old. In many ways, it's my newer role as a dad that's prepared me for our more recent progress at work. I already dread the day I have to explain what an active shooter is to my daughter, and I'm haunted by the notion that this country doesn't keep its kids safe.

Ultimately, the fear and vulnerability I feel as a parent is the sentiment that so many parents feel, the sentiment that has helped change the politics of guns.

for Gun Safety Myriad concerns over Trump's leadership fueled the 2018 suburban revolt against Republicans, but only health care ranked higher than guns as a priority for those who backed Democrats. Not only did Giffords PAC and Everytownfor Gun Safety outspend the NRA , candidates themselves spent their war chests on advertisements communicating their support for gun safety -- fueling an astonishing 22-fold increase from the last midterms in the number of spots promoting safer gun laws.

In suburban Minneapolis, voters learned how US Rep. Jason Lewis sided with the corporate gun lobby at the expense of his constituents. One ad from our organization featured a powerful testimonial from Burnsville, Minnesota, resident Bob Mokos, an Air Force veteran, NRA sharpshooter and a gun owner. In part because of the gun issue, Lewis is now a former congressman

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congressman. In the bellwether 6th Congressional District of Colorado, Mike Coffman accepted more NRA money than anyone else in his state. In one of our ads, we told the story that parents fear, that I fear -- the story of a text message from a child . It helped break through the noise of elections and connect those real fears to the real culprits in Congress who enabled our epidemic of gun violence to continue unchecked. In part because of these concerns, Coffman is now a former

That said, gun safety advocates shouldn't take full credit for the diametric shift of the politics in our favor. The gun lobby also has itself to blame. Today, the NRA is viewed by some as a pillar of the far-right conservative movement more focused on demagoguing than representing the beliefs of gun owners . No wonder 67% of the gun owners in a poll we conducted in 2017 feel that the NRA has been "overtaken by lobbyists and the interests of gun manufacturers and lost its original purpose and mission."

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To put in place the policies needed to make our country safer, Republicans need to decide whose side they're on -- and voters need to hold them accountable for those decisions.

Will Republicans continue to side with the NRA, which profits from the selling of guns? Or will they side with the parents who fear sending their kids to school, the students who hide in supply closets hoping that this time it's just a drill, the regular Americans who simply want their communities to be safe?

For now, the choice is theirs. But if 2018 taught us anything about gun safety, it's that voters will have the final say.