It should have been a high point in a career of high points: the premiere of a documentary chronicling how Kevin Johnson — the former N.B.A. All Star who, as mayor, helped rejuvenate this once-ailing capital city — kept the Sacramento Kings from leaving for Seattle with a gleaming new basketball arena.
But hours before the premiere last week, the ESPN network, which produced the documentary, “Down in the Valley,” announced it would delay indefinitely the national release of the film. The network cited the re-emergence of an issue that has shadowed Mr. Johnson since his first campaign in 2008: a claim by a woman that he sexually abused her 20 years ago, when she was 16 and he played for the Phoenix Suns.
On Tuesday night, Mr. Johnson, a Democrat, announced that he would not seek a third term next year, saying, “The city is headed in the right direction and is ready to embrace the exciting changes ahead.” No mayor in this city has ever served three terms.
Mr. Johnson has repeatedly denied the accusation and made no mention of it in his statement. In an interview on Friday, he asserted that the case was being dredged up by his opponents — including the teachers’ union, with which he has battled over the years — to hurt him politically.
“There are no truth to the allegations,” he said. “If you go back 20 years ago, they were investigated. Law enforcement obviously didn’t feel there was merit there. For me, I’ve just tried to move on and go forward.”
The Phoenix Police Department investigated the claim but closed the case without filing charges. Mr. Johnson entered a settlement that included a $230,000 payment to his accuser. The mayor declined to comment when asked why, if the charges were unfounded, he had agreed to make a payout.
What is different this time is a videotape of a police interview in which the girl, speaking in a calm voice, describes in disconcerting detail what she said Mr. Johnson did to her, including groping and undressing her. The release of the video, posted on Deadspin, a website devoted to sports news, put a young and vulnerable voice to claims that until now had been only a detached account found in court filings.
“People have so desperately wanted to believe in him that they’ve given him a pass on a lot of things, and I think that has worked out generally to the city’s advantage,” Steve Hansen, a Democratic City Council member and critic of Mr. Johnson’s, said before the announcement. “The wall of not knowing how to deal with his problems, but choosing to ignore the failures in hopes of the promise, has begun to collapse. Once you saw the video and read the story, it was hard to pretend it never happened.”
Mr. Johnson, 49, has long been a polarizing force in this city.
For his admirers, he is the vibrant face of a new Sacramento — epitomized by the $500 million arena going up on J Street, surrounded by a burst of construction inspired by the project. He is a former president of the United States Conference of Mayors and a regular guest of President Obama at the White House. He is married to Michelle Rhee, the high-profile school superintendent who, like Mr. Johnson, has a history of battling teachers’ unions.
He can barely walk from City Hall to a favorite hangout a block away, the Grange Restaurant and Bar, without getting stopped with a request for a photograph.