PHILADELPHIA — With Hillary Clinton poised to accept the Democratic Party's nomination for president, long-frustrated gun-control advocates see a new glimmer of hope for measures to restrict gun ownership and sales.

One of those hopefuls sits with Arizona's delegation to the Democratic National Convention here, his cane tucked under his seat at Wells Fargo Center. Throughout the convention, former U.S. Rep. Ron Barber has listened to gun-safety champions, and mothers who have shared their anguish over losing children to gun violence or excessive police force.

Wednesday night's convention programming highlighted the issue. The speakers included the mother of a victim of the recent Orlando nightclub massacre, the daughter of the principal of Sandy Hook Elementary School, who was killed in a 2012 mass shooting, and two survivors of last year’s Mother Emanuel Church shooting in Charleston, S.C.

Also speaking was Barber’s former boss.

While working as the district director for former U.S. Rep. Gabrielle Giffords, D-Ariz., in 2011, he was wounded alongside her at a constituent event near Tucson. Six people died and 13 were injured. Giffords was shot in the head.

Apart from the physical injuries to his left leg and face, the emotional trauma is always with him, Barber said. And the stories of fellow survivors and families of the victims tear at Barber.

"These are just very painful, just emotional experiences that you never get over," Barber, 70, said this week.

In early 2012, Giffords resigned from Congress to focus on her recovery and Barber won her seat in a special election. He was in Congress during the Sandy Hook Elementary School shootings in Newtown, Conn., where 20 children and six educators were shot dead. Barber later lost a bid to keep the seat to now-U.S. Rep. Martha McSally, R-Ariz.

"While I'm no longer in Congress, I'm very committed to this personally," he said. "My job, as I see it, is to continue to help keep this issue alive — to keep the concept of common-sense gun laws in play."

'Too many funerals'

After years of frustration, gun-control advocates feel the tide turning on the issue, which they believe maintains widespread popular support.

With confidence high about Democratic presidential candidate Hillary Clinton's prospects against Republican nominee Donald Trump, some see an opportunity — especially if Clinton's coattails can help Democrats retake the U.S. Senate.

Even in the U.S. House of Representatives, which could stay under GOP control even if the Democrats win the Senate, pressure is increasing. In June, U.S. Rep. John Lewis, D-Ga., led a Democratic sit-in on the House floor to demand action on gun control.

On Tuesday, Lewis joined Giffords, U.S. Sen. Chris Murphy, D-Conn., U.S. Sen. Chris Coons, D-Del., and mothers who have lost children to gun violence for an emotional rally at downtown Philadelphia's Logan Square park.

Lewis assured Giffords, his former House colleague, and the grieving mothers that the fight goes on. He encouraged the anti-violence activists to find a way of getting in the way, even if it means getting "in trouble, good trouble, necessary trouble."

"I've been to too many funerals in Atlanta, other parts of Georgia," Lewis said. "I've seen schoolmates and classmates and playmates of my son murdered and gone to their funerals. I'm sick and tired of the gun violence!"

On Capitol Hill, even the emotional toll of the Sandy Hook massacre was not enough to break the logjam. In the Senate, a bipartisan compromise on background checks stalled in 2013 and gun reform has been unable to get traction since.

"In the Senate, we were unable to break the Republican filibuster to pass a background-checks measure that was a watered-down version of what we really wanted to do, but that was supported by 90 percent of the American people," said Murphy, who emerged as a leading national voice on gun control after Sandy Hook.

Gun-control advocates pledged that day to build a political movement "that one day would be bigger, be badder and be stronger than anything that the gun lobby could put together," Murphy said.

Former U.S. Rep Gabby Giffords (center) stands with her husband and former NASA astronaut Mark Kelly (left) and Chelsea Clinton (Photo: Michael Chow/USA TODAY NETWORK)
Former U.S. Rep Gabby Giffords (center) stands with her husband and former NASA astronaut Mark Kelly (left) and Chelsea Clinton (Photo: Michael Chow/USA TODAY NETWORK)

Making the case at the convention

Murphy said he was proud the Democratic Party was "making the fight against gun violence a seminal part of our convention."

The convention has spotlighted gun-control advocates, including "the Mothers of the Movement" — pro-Clinton mothers who have lost children to gun violence or excessive force by police officers — on Tuesday night, and on Wednesday night Giffords and her husband, retired NASA astronaut Mark Kelly, Murphy, former independent New York City Mayor Michael Bloomberg and others. Vice-presidential nominee Tim Kaine mentioned the 2007 mass shooting at Virginia Tech in his acceptance speech and efforts to tighten gun laws in the wake of the tragedy.

When Giffords addressed the convention, she said: "Hillary is tough. Hillary is courageous. She will fight to make our families safer. In the White House, she will stand up to the gun lobby. That’s why I’m voting for Hillary."

Democrats at the convention adopted a platform that calls for expanding and strengthening background checks, closing “dangerous loopholes,” and keeping assault weapons and large-capacity ammunition magazines off the streets.

The platform also calls for the U.S. Centers for Disease Control and Prevention to have adequate resources to study gun violence as a public-health issue.

While the party's appeals for tighter gun measures are sharpening, the reality of significant changes is unclear. Political watchers say even if Clinton wins in November, any attempts for meaningful reform could be stymied by Congress.​

And gun-control advocates would have to reckon with the powerful National Rifle Association, which supports Trump and whose lobbyist has said Clinton wants to take away Americans' guns.

One political expert was skeptical that Democrats, even if Clinton wins the White House and the party's candidates take the Senate, would have the political strength needed to push through any major gun-control legislation.

However, given the public mood, the issue could resonate, said political observer David Berman.

In recent weeks, five police officers in Dallas were gunned down by a lone gunman, 49 people were massacred as they partied at a gay nightclub in Orlando and questions over police killings of black men have gripped the nation. The assailant in Florida had pledged his allegiance to the Islamic State.

Berman said gun control could possibly be a part of the first 100 days of a Clinton administration, a period when a new president historically hits the ground running with an agenda of legislative priorities.

"It seems like the public is starting to turn around a little more when it comes to some kind of gun control," said Berman, professor emeritus of political science at Arizona State University and a senior research fellow at ASU's Morrison Institute for Public Policy. "Hillary has made it a central plank. If she wins, she is going to say, 'It's my mandate.' She campaigned for gun control and I think that she's going to push for it."

'Not a complicated issue'

Trump has backed off earlier support of a ban on so-called assault weapons, saying Americans need to be able to protect themselves and that their right to bear arms shouldn't be curbed.

Clinton's position is there are changes that can be made to gun laws that still respect the Second Amendment.

Barber said he's confident that if Clinton is elected, stricter measures will come.

He cites surveys showing Americans increasingly support stricter gun laws by wider margins in the wake of the shootings around the country. An Associated Press-GfK poll released last week suggests most respondents support nationwide bans on semiautomatic weapons and the sale of high-capacity magazines that hold more than 10 bullets.

"It’s not a complicated issue — people try to make it one," Barber said. "The guy that shot us ... he just kept pulling the trigger, just kept firing away. So it's a firepower issue, as well."

Asked how gun-control advocates will make their case for changes, Barber told a story about the day of the massacre in Sandy Hook.

He was on the road to Cochise County to meet with constituents. He heard about the shooting as he was driving with his staff, and the death toll kept climbing.

Later, after the meeting, a man he has known for many years — a chile farmer — approached him.

"He said, 'I want to talk to you about what happened in Connecticut,' " Barber recalled. "He said, 'I've had a gun since I was a boy. I love hunting. I'm an NRA member — a lifetime NRA member.' "

The man told him he needed to go to Washington, D.C., "and do something about this."

Yvonne Wingett Sanchez and Dan Nowicki write for The Arizona Republic. Follow them on Twitter: @dannowicki and @yvonnewingett