"They complement one another and have so much energy," Johnson said of the couple. "They pull you into the project."
Rumsey clashes with some in his battles, such as State Rep. Stephen Barrar (R., Delaware). In January, protesters both for and against increased gun control gathered outside Barrar's office, and Barrar and Rumsey exchanged words. Barrar has said he does not believe more laws will stop criminals from using guns.
Sitting in the Springfield Friends Meeting House, where Delco United meets every month, Rumsey and Lasersohn finished each other's sentences. They spoke softly, contemplative yet assertive.
Cross-legged, a long peppered braid swept over her shoulder, Lasersohn said people don't have to be leaders to make an impact. She and her husband weren't, at first.
Rumsey grew up in Chester. It was a "hard town," Rumsey said, but he was raised in a working-class neighborhood where gun violence was not the norm.
"Kids fought in Chester. Rocks, sticks, and fists," Rumsey said. In today's Chester, "kids that age are in the morgue," he said. "That's because of guns."
Rumsey doesn't remember much about his father, David, who died when Rumsey was 2. Rumsey was raised by his mother, Katherine, a passionate Republican.
The Vietnam War - "a defining factor in our generation," Rumsey said - fueled his activism. His proudest efforts include helping Witness to Innocence, a Philadelphia-based group of exonerated death row inmates who protest against the death penalty.
Lasersohn, who grew up near Cleveland and attended Swarthmore College, met Rumsey 30 years ago while registering voters. Their work helped elect Chester's first Democratic mayor in nearly a century.
"We were attracted to each other's energy," Lasersohn said. They married in 1990 and have two daughters, now 19 and 21.
The couple's advocacy is all volunteer work. To make money, they founded Green Seeds, which helps nonprofits receive grants. Lasersohn also works as a preschool teacher.
Green Seeds isn't political. But, Rumsey said, "I'm not going to help raise money for things I don't believe in."
When it comes to gaining universal background checks on gun sales, as long as Rumsey and Lasersohn are at the helm, "I believe in my soul it will happen," Johnson said.
Elaine Vetre, treasurer of Delco United, applauded the pair's commitment. But Rumsey's passion is personal. His children from a previous marriage had a stepfather who died by suicide with a gun.
Polls, such as one by ABC News-Washington in 2013, have found widespread public support for expanding background checks. Ten of Pennsylvania's 11 congressional representatives, including Patrick Meehan (R., Delaware), agree. Meehan said he signed on to the most recent universal background check bill, looking for the most effective means to keep the public safe. Yet such bills have failed time and time again.
To gain support, the couple and 150 people from Delco United trekked the seven miles from Chester to Media in June. They passed 100 people openly carrying semiautomatic rifles and holstered handguns, as the gun safety champions sang "We Shall Overcome."
Johnson was weeping. If universal background checks had been law, she said, her son would be alive today.
Media Mayor Bob McMahon said Rumsey's fervor has not wavered in 30 years.
"There were times Terry and I weren't on the same page," McMahon said. "But I learned a lot from him."
After a tragedy, many demand action. But then, Lasersohn said, time quells passion. What keeps the couple going?
"When you hear stories of parents who lost children," Rumsey said.
"We will win universal background checks."