In a city where David’s righteousness almost never beats Goliath’s might, what Nicole Hockley and the other Sandy Hook families did to the gun lobby last week was nigh unto miraculous.

Gun-control legislation had appeared to be a lost cause. But over the course of four days, Hockley, who lost her 6-year-old son, Dylan, in December, joined with 10 other kin of the Newtown dead — and brought the legislation back to life.

Last Sunday, the families appeared on “60 Minutes.” On Monday, Hockley introduced President Barack Obama at an event in Connecticut. The families then flew to Washington on Air Force One to begin their lobbying — emotionally grueling meetings with 26 senators, Republicans and Democrats, over three days.

By Thursday morning, a Republican-led filibuster of the gun legislation had been soundly defeated. Obama called the family members immediately after the vote to thank — and credit — them for the reversal of fortunes. The legislation’s supporters in the Senate did, too.

“They spent all week fanning out across the Capitol,” said Sen. Chris Murphy, D-Conn., “and I think it’s no coincidence that we will end this week in a much better position than people thought we would a week ago.”

Lobbyists like this would be worth millions on K Street — but Hockley and her peers succeeded precisely because they weren’t the usual actors following the usual script. “At the start of the week I didn’t even know what a filibuster was,” Hockley told me Thursday.

Other factors were involved. Obama, after a slow start, stepped up his pressure on Congress. Opponents changed tactics, too, calculating that it would be easier to defeat the bill by amending it on the Senate floor than by blocking its consideration. Indeed, the legislation still faces an uncertain future in the Senate and daunting odds in the Republican-led House.

Still, it’s worth pausing to celebrate an against-the-odds moment in the capital. Hockley’s group, Sandy Hook Promise, is advised by a skilled Washington hand, Ricki Seidman, but many of the parents involved knew one another from playing ultimate Frisbee.

They decided to avoid the most contentious issues (they don’t favor a ban on assault weapons) and, instead of using pressure tactics, told the senators stories about the dead and shared photos.

“They didn’t expect that,” said Tim Makris, co-founder of Sandy Hook Promise and father of a fourth-grader who survived the attack. “They expected banging on the tables.” The families are said to have been instrumental in the compromise about background checks between Sens. Pat Toomey, R-Pa., and Joe Manchin, D-W.Va., that revived the legislation’s prospects.

The stories lawmakers heard are much like those the families told on “60 Minutes,” where Hockley said she put her son’s ashes in an urn on her bedroom dresser: “Every night I beg for him to come to me in my dreams so that I can see him again. And, during the day, I just focus on what I need to do to honor him and make change.”

The day after the show aired, Obama, speaking in Connecticut, repeated those words of Hockley’s. “If Nicole can summon the courage to do that, how can the rest of us do any less?” he asked.

Her story was again the focus of attention Wednesday. In his maiden speech on the Senate floor, Murphy described the close relationship between Dylan, who was autistic, and his special-ed teacher, Anne Marie Murphy (no relation). “When the bullets started flying, she brought Dylan into her arms,” he said. “And that is just how the two of them were found.”

Although the families’ lobbying was private, two of them, Erica Lafferty (who lost her mother, Principal Dawn Hochsprung) and Jillian Soto (who lost her sister, Victoria, a teacher), appeared at a news conference with senators before Thursday’s vote.

Hockley wasn’t at the news conference, but the lawmakers invoked her name yet again. “Newtown has changed us,” said Sen. Richard Blumenthal, D-Conn. “As Nicole Hockley said, there is no going back now.”

When I caught up with Hockley on Thursday afternoon, she was tired and eager to return to her husband and surviving son. She had postponed the interview to take the president’s call, but Hockley, a stay-at-home mom with a background in marketing, wasn’t impressed by that or by all the lawmakers’ attention.

“This has been quite a whirlwind,” she said, “but honestly I would rather be at home with Dylan.”

Dana Milbank is an American political reporter and columnist for The Washington Post. Email to danamilbank@washpost.com.