Since the issue resurfaced in June in the first set of Democratic presidential debates, The New York Times has unearthed and reviewed more than four decades of Biden’s voting record and statements about the issue. Below is a brief timeline of highlights.

— A Turning Point

1974: Biden, who was then a senator for Delaware, voted two times to protect court-ordered busing to achieve desegregation, including the decisive vote on an amendment that would have effectively done away with it.

But months after an angry crowd in a school auditorium criticized him for that vote, Biden said in a speech on the Senate floor that he had become “more and more disenchanted with busing as a remedy.”

— Alliances With Segregationists

1975: Biden joined Sen. Jesse Helms, a Republican segregationist from North Carolina, in supporting an antibusing amendment to an education spending bill. When the amendment failed, Biden wrote a narrower measure that prevented schools from using federal dollars to assign teachers or students by race. It passed 50-43.

In a television interview, Biden called busing an “asinine concept” and said he had “gotten to the point where I think our only recourse to eliminate busing may be a constitutional amendment.” As an alternative, he argued for putting “more money into the black schools” and opening up housing patterns, warning that otherwise “we are going to end up with the races at war.”

“You take people who aren’t racist, people who are good citizens, who believe in equal education and opportunity, and you stunt their children’s intellectual growth by busing them to an inferior school and you’re going to fill them with hatred,” he said in the interview.

“The new integration plans being offered are really just quota systems to assure a certain number of blacks, Chicanos or whatever in each school. That, to me, is the most racist concept you can come up with.

“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?”

1976: Biden introduced legislation to prevent the Justice Department from pursuing desegregation cases that could result in court-ordered busing.

“I oppose busing, to the chagrin of some of my liberal colleagues,” he said.

The same year, Biden supported several bills designed to limit the power of federal judges who could issue busing orders.

1981-82: Biden partnered with Sen. Strom Thurmond, R-S.C., another staunch segregationist, to introduce a provision into the Justice Department’s spending bill that effectively barred federal courts from issuing busing orders. It passed the Senate but died in the House.

During a Senate hearing, Biden said no issue had “consumed more of my time and energies” than busing during his first eight years in office. “We want to stop court-ordered busing” without undoing the Brown ruling, he said.

— Looking Back

2007: In his memoir “Promises to Keep: On Life and Politics,” Biden revisited busing in Delaware in the 1970s. He called the matter a “liberal train wreck” that was “tearing people apart,” and said that both black and white parents were “terrified.”

Busing ended in Wilmington, Delaware, Biden’s hometown, in 1995 after 17 years of federally mandated measures. The state has since passed a law saying children should attend the schools closest to their homes.

— The 2020 Presidential Race

June 27: Harris challenged Mr. Biden directly about his position on busing during the first Democratic debates, saying his alliances with segregationists were especially “hurtful” to her as a black woman who had been bused to integrate schools in Northern California. Afterward, on MSNBC, Biden said his position had been “mischaracterized.”

“I supported busing to eliminate de jure segregation,” he said, meaning segregation imposed by law, as opposed to “de facto” segregation, which occurs because of segregated housing patterns, for example.

June 28: At a conference in Chicago, Biden repeated his defense, saying, “I’ve always been in favor of using federal authority to overcome state-initiated segregation.” He also drew a distinction between court-ordered busing and programs initiated by local communities. “I never, never, never ever opposed voluntary busing,” he said.

July 5: Biden told CNN that he thought busing did not work. “You had overwhelming response from the African American community in my state,” he said, adding, “They did not support it.”

This article originally appeared in The New York Times.