Just two years after narrowly winning a Senate seat at age 29, Biden had recently cast two votes to protect the practice of busing to achieve desegregation — despite his own very public unease with it. He thought he had come to Newport simply to address a local civics organization. But when he got there, more than 200 people, organized by a largely white parent group that opposed busing, jeered and heckled Biden, demanding that he more vocally join their cause.

“If you think I’m in trouble with you people,” he said then, seeking to assure the crowd that he was on their side, “you ought to hear what my liberal friends are telling me.”

The meeting marked a turning point for the young senator, who counted himself a liberal Democrat and an ardent defender of civil rights. Not long after that verbal drubbing, Biden plunged headfirst into one of the most politically fraught and racially divisive topics in America. He emerged as the Democratic Party’s leading anti-busing crusader — a position that put him in league with Southern segregationists, at odds with liberal Republicans and helped change the dynamic of the Senate, turning even some leaders in his own party against busing as a desegregation tool.

“No issue has consumed more of my time and energies,” Biden declared with a flourish as he opened a Senate hearing in 1981, adding, “We want to stop court-ordered busing.”

More than four decades later, that vocal advocacy clouds the early stages of Biden’s 2020 presidential run. In the two weeks since Sen. Kamala Harris of California, a rival for the nomination, invoked her own story of being bused to school to forcefully challenge Biden during the first Democratic presidential debates — and on the heels of criticism of his work with segregationists on crime legislation — Biden’s standing has dropped among the Democratic electorate, and his status as the race’s early front-runner is freshly threatened as his polling lead among black voters softens.

Biden declined to be interviewed for this article. On Friday, however, his campaign told Politico that Biden now backs an effort by Democrats in Congress to repeal 1970s-era restrictions on voluntary busing. That is the type of desegregation method Harris experienced as a child, and Biden’s position is not a shift: He has never opposed voluntary busing.

During the course of his 36-year Senate career, school desegregation, more than any other issue with the possible exception of crime, crystallized the political and civil rights crosscurrents swirling around Biden. He arrived in Washington in 1973, having come of age amid the racial ferment of the late 1960s, with deep ties to Wilmington’s black community — relationships rooted in his advocacy for housing integration and other forms of urban aid in a state still grappling with the legacy of Jim Crow.

Biden has said that his record on school desegregation has been misrepresented, and he maintains that he supported busing as a remedy for the intentionally discriminatory policies that kept white and black students in separate schools in the South — a position his campaign spokesman, Andrew Bates, reaffirmed Sunday in a statement to The Times. But a review of hundreds of pages of congressional records, as well as interviews with education experts and Biden contemporaries in Wilmington and Washington, suggests that his opposition to busing was far more sweeping than he has led voters to believe.

“I don’t know whether he’s just reconstructed this history in his own mind, but he’s factually untruthful, that’s for sure,” said Gary Orfield, a professor who has written extensively about school desegregation, including in Wilmington, and who testified before Biden in 1981. He said that for politicians like Biden, the busing question was “a real test of conscience and courage. I think he failed.”

Biden also, more than any other Northern Democrat, adopted the language of conservatives on the issue, using terms like “forced busing” when his fellow liberals would emphasize desegregation, not transportation. Civil rights advocates note that students had, of course, been riding buses to school for decades; opponents of court-ordered busing never raised a ruckus when black children were forced to ride buses miles away from their homes to attend “colored-only” schools.

“I oppose busing,” Biden said in a television interview entered into the Congressional Record in 1975. “It’s an asinine concept, the utility of which has never been proven to me.”

From 1975 until 1982, Biden — often in partnership with his fellow Delawarean, Sen. William Roth, a Republican — promoted nearly a dozen pieces of legislation aimed at placing strict limits on the authority of federal agencies and the courts to mandate busing to achieve racial integration in schools. At a time when busing controversies were provoking racial unrest in cities like Boston, Biden argued that housing integration — which would take much longer to implement than a busing plan — was a far better way to desegregate public schools.

“The new integration plans being offered are really just quota-systems to assure a certain number of blacks, Chicanos, or whatever in each school,” Biden told the interviewer.

“That, to me, is the most racist concept you can come up with,” he added. “What it says is, in order for your child with curly black hair, brown eyes, and dark skin to be able to learn anything, he needs to sit next to my blond-haired, blue-eyed son. That’s racist! Who the hell do we think we are, that the only way a black man or woman can learn is if they rub shoulders with my white child?”

The Supreme Court’s landmark decision in Brown v. Board of Education upended the American educational landscape, reversing decades of the “separate, but equal” doctrine with its finding that racially segregated schools were unconstitutional. Biden was 11 years old and had just moved with his family to Delaware from Scranton, Pennsylvania, when the unanimous ruling came down in May 1954.

The case had an immediate impact throughout the country. But it was particularly resonant in Delaware, a state that, while not in the Confederate South, had laws on its books that required its public school pupils to attend segregated schools. A desegregation suit filed in Delaware had been one of five cases the Supreme Court merged in hearing Brown.

After the Brown decision, Louis Redding, a black lawyer who had handled the Delaware suit, set out to test the state’s commitment to desegregation. He recruited a group of 11 black students to try to enroll in an all-white high school in Milford, a city in one of the more conservative areas of the state.

The group lasted 28 days before being forced out.

Busing in Wilmington ended in 1995 when, after 17 years of federally mandated integration measures, the state education board successfully argued to be released from oversight. The state Legislature has since passed a law stating every child should attend the school closest to their home, which was seen as the death blow for the final vestiges of the state’s busing era.

The Biden spokesman, Bates, said that if elected, Biden would reinstate Obama-era policies “designed to increase the diversity our schools.” Biden has long maintained that the white flight he had warned about came to pass, noting the many white families who fled to Pennsylvania for that state’s public schools, or — like Biden himself — enrolled their children in private schools. In his 2007 memoir, he described court-ordered busing as “a liberal train wreck.”

Aides say he has not changed his mind.

This article originally appeared in The New York Times.