LAS VEGAS — In at least three campaign appearances over the past two weeks, Joseph R. Biden Jr. has told a similar story as he tries to revive his campaign in states with more diverse voters. On a trip to South Africa years ago, he has said, he was arrested as he sought to visit Nelson Mandela in prison.
“This day, 30 years ago, Nelson Mandela walked out of prison and entered into discussions about apartheid,” Mr. Biden said at a campaign event in South Carolina last week. “I had the great honor of meeting him. I had the great honor of being arrested with our U.N. ambassador on the streets of Soweto trying to get to see him on Robbens Island.”
Mr. Biden referred to his own arrest twice more in the next seven days, including at a campaign stop here on Tuesday where he spoke of getting arrested in South Africa between efforts to coax his wife to marry him. That proposal occurred in 1977, both Bidens have said.
But if Mr. Biden, then a United States senator from Delaware, was in fact arrested while trying to visit Mr. Mandela, he did not mention it in his 2007 memoir when writing about a 1970s trip to South Africa, and he has not spoken of it prominently on the 2020 campaign trail. A check of available news accounts by The New York Times turned up no references to an arrest. South African arrest records are not readily available in the United States.
Andrew Young, a former congressman and mayor of Atlanta who was the U.S. ambassador to the United Nations from 1977 to 1979, said that he had traveled with Mr. Biden over the years, including to South Africa. But Mr. Young said that he had never been arrested in South Africa and expressed skepticism that members of Congress would have faced arrest there.
“No, I was never arrested and I don’t think he was, either,” Mr. Young, now 87, said in a telephone interview.
Mr. Young added: “Now, people were being arrested in Washington. I don’t think there was ever a situation where congressmen were arrested in South Africa.” He emphasized his great respect for Mr. Biden, though he said he was currently supporting former Mayor Michael R. Bloomberg of New York for the presidency.
Former Senator Gary Hart, a Democrat from Colorado who joined the Senate in 1975 and who was a vocal opponent of apartheid, said in a brief phone call, “I know nothing about that,” when asked about Mr. Biden’s account.
The Times could not account for all of the details of Mr. Biden’s overseas travel during the period that included the South Africa trip. Mr. Biden’s campaign did not respond to five efforts to seek comment and clarification.
Mr. Biden’s repetition in recent days of the story about an arrest in South Africa comes as he confronts challenging political headwinds. Once the national front-runner, he turned in disappointing results in Iowa and New Hampshire, two heavily white states, where he finished fourth and fifth, respectively. His campaign is banking on at least a second-place finish in Nevada on Saturday and a victory in South Carolina, two diverse states where voters of color play crucial roles. He regularly uses his remarks to try to connect with black voters, such as saying in Nevada and elsewhere that he was “raised in the black church.’'
In South Carolina in particular, Mr. Biden is pinning his hopes on a strong showing with African-American voters, a constituency with which he polled strongly throughout much of the race, though he now faces increasing competition for the support of black voters.
After recounting the story of his arrest while campaigning in South Carolina last week, Mr. Biden subsequently told it twice more in Nevada, mistakenly saying Robbens Island instead of Robben, where Mr. Mandela was held for much of his 27-year imprisonment.
And on Sunday, as he had in South Carolina, he also delivered a coda to the story.
“After he got free and became president, he came to Washington and came to my office,” Mr. Biden said of Mr. Mandela at a black history awards brunch in Las Vegas. “He threw his arms around me and said, ‘I want to say thank you.’ I said, ‘What are you thanking me for, Mr. President?’ He said, ‘You tried to see me. You got arrested trying to see me.’”
On Tuesday, speaking in Las Vegas at an event with Asian-American and Pacific Islander voters, he said that he “came back from South Africa, trying to see Nelson Mandela and getting arrested for trying to see him,” right before he received an answer to his marriage proposal from his now-wife, Jill Biden.
Mr. Biden has previously discussed visiting South Africa as a young senator — but his emphasis in discussing his travel there has not been on an arrest.
In a December 2013 clip from CBS News, Mr. Biden, expressing admiration for Mr. Mandela, mentioned a congressional delegation trip he took to South Africa. He also described being thanked, years later, by the iconic civil rights leader, but did not mention his own arrest. Instead, he said Mr. Mandela expressed gratitude for his support of anti-apartheid sanctions.
In a 2013 statement marking the death of Mr. Mandela, Mr. Biden, then vice president, recalled how he had traveled to Soweto with Mr. Young, but he did not mention an arrest.
“I saw his world the way it used to be when I visited South Africa as a 34-year-old senator,” the statement said. “When I exited the plane I was directed to one side of the tarmac, while the African-American congressmen traveling with me were sent to the other side. I refused to break off, and the officials finally relented. When I tried to enter Soweto township with Congressmen Andrew Young of Atlanta and Charles Diggs of Detroit, I remember their tears of anger and sadness.”
Mr. Young, in the phone interview, said he did encounter discrimination on his trips to South Africa over the years, but said, “I would not forget going to jail, but I know I did not ever go to jail in South Africa.”
Mr. Biden and Dr. Biden wrote about a South Africa trip in their memoirs, too. According to their accounts, Mr. Biden went there after giving Dr. Biden an ultimatum following multiple marriage proposals. They both have said that Mr. Biden sought a response when he returned from the trip.
Neither Mr. Biden nor Dr. Biden mentioned an arrest when describing the proposal.
“The 10 days in Africa felt like forever,” Mr. Biden wrote in his book “Promises to Keep.” “I had gotten through worse, but I knew that if Jill said no, it was going to hurt like hell.”
It was in that context — a lighthearted retelling of multiple marriage proposals — that Mr. Biden brought up Mr. Mandela at the campaign event on Tuesday.
“When I came back,” he said, “first thing I did, I landed in Philadelphia and I went back to her apartment.”
Last year, Mr. Biden faced scrutiny after The Washington Post reported that he had misstated details in a story about the war in Afghanistan that he told on the campaign trail.
Former Senator Bob Kerrey, a supporter of Mr. Biden’s who joined the Senate in 1989 as a Democrat from Nebraska, suggested that perhaps there could have been an arrest of senators but no charges by the government, and noted, “a step away from arrest is to be detained.”
“I had some senators I wish had been arrested,” Mr. Kerrey joked in a phone interview. “He’s not on that list.”
But he said that he had never heard the story before.
Kitty Bennett contributed research.