Mr. Jaber’s visit — and that of the Pakistani family — comes as a congressional effort is building to force the administration’s hand. Early this month, the Senate Intelligence Committee added to the annual intelligence policy bill a requirement for an annual report giving the number of “combatants” and “noncombatant civilians” killed or injured in the previous year in drone strikes outside conventional wars. The report would give only total numbers, not details of each strike or the names of those killed.

Mr. Schiff, who met Mr. Jaber on Wednesday, plans to sponsor a similar bill in the House.

Mr. Jaber’s visit was sponsored by the peace group Code Pink, which organized an accompanying protest in front of the White House last week, and Reprieve, a human rights group based in London.

Unlike some of the activists who embraced him and apologized to him wherever he went, Mr. Jaber strikes a very humble and unassuming attitude about his family’s tragedy. He says he does not presume to pass judgment on the drone strike program itself, but wants acknowledgment and an apology.

“I learned two things,” he said when asked to sum up his week in Washington. “First, the American people and their organizations are very kind and well meaning, and the Congress members also were very sympathetic. But on the other side, there are politicians who seem to be trying to keep everything secret.”

Mr. Jaber offers a harrowing account of the drone strike. It was the day after his son’s wedding in his native village, Khashamir, and he was eating dinner at home with several relatives when they heard a whirring from the sky. Looking out the window, he and his relatives saw a flash, and then heard a series of terrific crashes, “as if the whole mountain had exploded.” The village erupted in panic.

Mr. Jaber’s daughter, who was very close to the strike, was so traumatized that she did not get out of bed for three weeks, he said. The mother of one of the dead men went into a coma after she heard the news and died a month later.