WASHINGTON — Nearly a month after Rob Porter, the White House staff secretary, resigned amid accusations of domestic abuse, John F. Kelly, the president’s chief of staff, acknowledged on Friday that he had stumbled in response to initial reports of the allegations.

“We didn’t cover ourselves in glory,” Mr. Kelly, who had issued a statement in Mr. Porter’s defense, told a group of reporters gathered in his office. He said that Mr. Porter had “presented himself as the ultimate gentleman” while he worked at the White House.

“I never saw him mad or abusive in any way,” Mr. Kelly said.

The White House has struggled to clarify who knew what about Mr. Porter and when. Mr. Kelly, who worked closely with Mr. Porter and eventually accepted his resignation, had declined to publicly clear up the matter, even as the case exposed internal frustrations with his sharp-elbowed attempts to end dysfunction in the West Wing.

On Friday, Mr. Kelly offered his version of the events, adding to the White House’s ever-winding timeline on Mr. Porter while leaving many questions unaddressed. This time, Mr. Kelly agreed with a chronology provided by Christopher A. Wray, the director of the F.B.I., who said that information about Mr. Porter had been delivered to the White House security office nearly a year ago.