(WASHINGTON) -- Gun control advocates making their last-minute preparations for a lobbying trip to Capitol Hill were shaken by the mass shooting that claimed the lives of 12 people at the Washington Navy Yard on Monday. Nine months after the Sandy Hook Elementary School massacre that left 26 dead, including 20 children, many of those grieving families plan to return to Washington to try to jumpstart an issue that seems to have lost some of the urgency it had.
"It all comes flooding back to you," said Darren Wagner, the father of two children who survived the Newtown, Conn., shooting. "It makes me angry as a dad, as a police officer, as a first responder."
Wagner, a former police officer, is one of more than 90 advocates with Newtown Action Alliance who are scheduled to arrive in Washington Tuesday in a pre-planned trip to jump start conversations in Congress on background check legislation.
They have more than 40 meetings planned with Congressional offices this week, and plan to hold a press conference with Newtown families on Wednesday. A rally with gun control group Mayors Against Illegal Guns is planned for Thursday.
But both this latest mass shooting and the lobbying push come at a pivotal time for gun control advocates.
They are coming off of a major loss last week after two Colorado State legislators were recalled in an effort to punish them for supporting legislation that strengthened background checks and put in place restrictions on certain magazine sizes.
That fight was lost despite millions spent to defend the lawmakers by gun control advocacy groups and Democrats.
And with Congress officially back in session after the August recess, they hope to keep the pressure up on lawmakers to support a second attempt at national background check legislation after the first attempt failed in April.
Meanwhile, other issues like military action in Syria, the looming debt ceiling, and a government funding bill have all pushed gun control to the back burner.
This moment is now one that could help reset the narrative.
"If you work with survivors every day you can't help but feel a blow to the gut when this happens again," said Mark Glaze, director of Mayors Against Illegal Guns, one of the most active gun control groups working to push new laws in Congress and around the country.
"And every time there's another mass shooting, senators who read from the [National Rifle Association's] talking points rather than listening to their constituents ought to be asking themselves some tough questions," he said.
Since Newtown, there have been five mass shootings that have left five or more people dead, and the Navy Yard shooting has become the largest of those. But the successive incidents haven't yet managed to move votes in Congress.
Both sides know that the more time passes after a tragedy, the more difficult efforts to pass gun control legislation become.
"Their best chances of passing things are after an atrocious crime and when emotions are high and when they can ram something through without the opportunity for debate and careful consideration," said Dave Kopel, a lawyer and research director at the Independence Institute who is the lead attorney for the legal challenge to Colorado's new gun control laws.
"The core impulse of the anti-gun movement is guns are bad and so whenever evil acts are done with guns that proves we need more laws against guns," he said. "The specifics aren't really important."
This week was also expected to be a high profile testing ground for expanding the gun control advocacy agenda to include opposing "Stand Your Ground" laws, which some believe played a role in the death of teenager Trayvon Martin and the acquittal of the man who killed him, George Zimmerman.
A Senate hearing was initially planned to address Stand Your Ground laws on Tuesday, but was postponed due to the tragedy at the Navy Yard -- an irony in itself for many gun control advocates.
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