Joe Biden was a freshman senator, the youngest member of the august body, when he reached out to an older colleague for help on one of his early legislative proposals: The courts were ordering racially segregated school districts to bus children to create more integrated classrooms, a practice Biden opposed and wanted to change.

"I want you to know that I very much appreciate your help during this week's Committee meeting in attempting to bring my antibusing legislation to a vote," Biden wrote on June 30, 1977.

The recipient of Biden's entreaty was Sen. James Eastland, at the time a well-known segregationist who had called blacks "an inferior race" and once vowed to prevent blacks and whites from eating together in Washington. The exchange, revealed in a series of letters, offers a new glimpse into an old relationship that erupted this week as a major controversy for Biden's presidential campaign.

Biden on Wednesday night described his relationship with Eastland as one he "had to put up with." He said of his relationships with Eastland and another staunch segregationist and southern Democrat, Sen. Herman Talmadge of Georgia, that "the fact of the matter is that we were able to do it because we were able to win — we were able to beat them on everything they stood for."

But the letters show a different type of relationship, one in which they were aligned on a legislative issue. Biden said at the time that he did not think that busing was the best way to integrate schools in Delaware and that systemic racism should be dealt with by investing in schools and improving housing policies.

The letters were provided Thursday to the Washington Post by the University of Mississippi, which houses Eastland’s archived papers. They were reported in April by CNN.

Biden's campaign late Thursday issued a statement saying that "the insinuation that Joe Biden shared the same views as Eastland on segregation is a lie."

"Plain and simple. Joe Biden has dedicated his career to fighting for civil rights," the statement said.

The controversy over Biden's comments this week have continued to reverberate at a crucial time in the campaign, with matters of race dominating the political discussion ahead of several prominent gatherings, including the first presidential debate next week and a multicandidate event before black voters in South Carolina on Friday. It has emerged as a complex political problem for Biden, who has been trying to campaign as a civil rights champion while explaining past views that are out of step with today's Democratic base.

Biden's Wednesday remarks sparked one of the sharpest intra-Democrat exchanges of the campaign, when Sen. Cory Booker of New Jersey, one of his black 2020 rivals, criticized both Biden's work with segregationists and the language that he used in describing it.

On Wednesday, Biden called Booker. Biden's campaign also distributed talking points to supporters, emphasizing that Eastland and Talmadge "were people who he fundamentally disagreed with on the issue of civil rights."

Late Thursday, the former vice president met with a small group that included black members of Congress, one of the participants said.

Divisions also emerged in Biden's campaign over how he should handle such situations. Aides alternately argued that he simply misspoke in telling the anecdote, that he shouldn't be telling it at all or that his remarks demonstrate his ability to work with those with whom he disagrees and the words were being purposefully twisted for political gain.

The letters show that Biden's courtship of Eastland started in 1972, before he had taken office, and that he wrote to the older senator listing his top six committee assignment requests, with Foreign Relations and Judiciary at the top. A few weeks later, Biden thanked Eastland, writing that he was "flattered and grateful" for his help. He also referred to the December 1972 car crash that killed his wife and daughter and injured his two sons.

"Despite my preoccupation with family matters at this time, I intend to place the highest priority on attending to my committee responsibilities," Biden wrote.

Biden supporters have repeatedly pointed to his efforts on civil rights issues to cast him as a champion of equality. Not only did he share an eight-year partnership with the first black president, he also worked alongside black leaders throughout his career on extending the Voting Rights Act, amending the Fair Housing Act and creating the holiday honoring the Rev. Martin Luther King Jr.

Yet in the debate over the merits of busing as a solution to greater integration, Biden's avowed stance against it put him at odds with some civil rights leaders.

It was in that context that he courted the support of Eastland — at the time the chairman of the Senate Judiciary Committee — as well as other senators.

In one letter, on March 2, 1977, Biden outlined legislation he was filing to restrict busing practices.

"My bill strikes at the heart of the injustice of court ordered busing," he wrote to Eastland. "It prohibits the federal courts from disrupting our educational system in the name of the constitution where there is no evidence that the governmental officials intended to discriminate."

"I believe there is growing sentiment in the Congress to curb unnecessary busing," he added. The Senate two years earlier had passed a Biden amendment that prohibited the federal Department of Health, Education and Welfare from ordering busing to achieve school integration.

"That was the first time the U.S. Senate took a firm stand in opposition to busing," Biden wrote. "The Supreme Court seems to have recognized that busing simply cannot be justified in cases where state and local officials intended no discrimination."

In later letters to Eastland, Biden continued pushing his legislation.

"I want you to know that I very much appreciate your help during this week's Committee meeting in attempting to bring my antibusing legislation to a vote," Biden wrote on June 30, 1977.

The next year, he continued to push for antibusing legislation and again wrote to Eastland.

"Since your support was essential to having our bill reported out by the Judiciary Committee, I want to personally ask your continued support and alert you to our intentions," Biden wrote on Aug 22, 1978. "Your participation in floor debate would be welcomed."

After Biden’s remarks at the Wednesday night fund-raiser, advisers played down his comments about Eastland as a garbled rendition of a familiar Biden anecdote. In particular, they sought to excuse Biden for saying that Eastland didn’t refer to him as “boy” — an insult leveled at black men — but as “son.”

"He just misspoke," said one Biden adviser. "The way Biden usually tells the story, he says Eastland didn't call him 'senator,' he called him 'son,' " the adviser said. "Eastland called him 'boy' and 'son' also. This was Eastland's way of diminishing young senators."

In the campaign statement Thursday, Biden's national press secretary, Jamal Brown, said Biden's "strong support for equal housing, equal education and equal job opportunities were clear to all Delawareans in the 1970s."

Biden sought to ensure that black students received "the resources necessary to deliver the quality education they deserved," he said.

Brown added that throughout his public life, Biden "fought the institutional problems that created de facto segregated school systems and neighborhoods in the first place: redlining, school lines drawn to keep races and classes separate and housing patterns and discrimination."

Almost the entire Democratic field is set to attend a fish fry Friday night hosted by House Majority Whip James Clyburn, a leading black figure in the state and one who has remained supportive of Biden.

It would be the first public appearance Biden is making with the same Democratic presidential hopefuls who have heaped criticism on him for the comment.

In demanding an apology, Booker said Wednesday that Biden's "relationships with proud segregationists are not the model for how we make America a safer and more inclusive place for black people, and for everyone."

Asked about Booker's remarks by reporters, Biden declined to offer an apology and instead demanded one from Booker. The two men later spoke privately.

“Cory shared directly what he said publicly — including helping Vice President Biden understand why the word ‘boy’ is painful to so many,” said Sabrina Singh, a Booker campaign spokeswoman. “Cory believes that Vice President Biden should take responsibility for what he said and apologize to those who were hurt.”

Biden's campaign would not elaborate on the call, but it is clear the topic could linger over the coming days.

Biden has scheduled a sit-down interview with MSNBC, his campaign has been sending out talking points to surrogates, and some black supporters are eager to hear the former vice president offer a fuller explanation.

"I think he's got to address it head on and show people what his line of thinking was," said Antjuan Seawright, a Democratic strategist in South Carolina who is close with Biden's team. "I don't think they need to get off course with their strategy. I just think they have to address it as it comes up and move on."

Other Biden supporters, however, think he's taking just the right approach and standing by his long-held beliefs.

"I encouraged campaign staff that I know to say: 'Don't back off on this. This is precisely why you're the right guy in the right place at the right time.' And I was glad to see that he didn't," said Dave O'Brien, a longtime Biden supporter in Cedar Rapids, Iowa.

“You know that some of the other issues, he’s got to evolve with the times, which he has,” O’Brien added. “But there are points where you need to make a stand, so I was very glad to see him not back off on this issue.”