For years, Sotheby’s auction house has tried to sell the papers, manuscripts and personal library of the Reverend Martin Luther King Jr.

But previous negotiations with various institutions came to naught, including a private sale in 2003 that was called off. Now, on June 30, Sotheby’s will auction the King collection, hoping that an institution will step forward and pay from $15 million to $30 million for the lot of more than 10,000 items.

“It does set a challenge for American institutions to decide whether or not they want to save and preserve the King legacy for posterity,” the vice chairman of Sotheby’s, David Redden, told the Associated Press Wednesday night.

“This is a very important story that needs a very appropriate conclusion,” he said.

Sotheby’s was to make a formal announcement about the sale yesterday.

The money will go to the financially strapped King estate. Redden said the death of Coretta Scott King earlier this year helped speed up the decision to hold an auction.

“To be candid,” Mr. Redden said, “the passing of Mrs. King did require that the estate put their affairs in order.”

The papers span from 1946 to 1968, the most important years of King’s life. They include 7,000 handwritten items, including his early Alabama sermons and a draft of the speech, “I Have a Dream,” which he delivered Aug. 28, 1963, at the massive March on Washington for Jobs and Freedom.

King’s personal library of approximately 1,000 volumes is also part of the compendium as well as 800 index cards from his days as a graduate student. On the cards, he wrote facts, aphorisms and biblical quotes.The entire collection will be on public view June 21-29, in anticipation of the sale on June 30.

Historians believe it is one of the greatest American archives of the 20th century in private hands and reveals a fuller portrait of King, the Nobel Prize winner who led the Civil Rights movement, helped dismantle segregation and was gunned down in 1968.

“King was at the center of one of the most important periods in American history and these documents illuminate the era,” said Stanford history professor Clayborne Carson, who edited the “The Autobiography of Martin Luther King, Jr.”

Mr. Carson said one the most memorable writings was a draft of King’s Nobel Prize acceptance speech, which he won at age 35. In his address, King said: “Nonviolence is the answer to the crucial political and moral questions of our time – the need for man to overcome oppression and violence without resorting to violence and oppression.”

Given the historical significance of the papers, Mr. Redden believes a major institution, aided by a donor, will buy the lot. He said the estate doesn’t want King’s work to fall into private hands.

“The estate very much wants this to go to an institution,” he said.

Mr. Redden declined to name a possible buyer. But it’s likely that a top university, the Smithsonian Institution or the Library of Congress would bid on the collection.

“If our institutions can’t afford it, then something is intensely wrong,” Redden said.

Mr. Redden said the King scenario is similar to the National Library of Ireland which bought previously unseen manuscripts of James Joyce’s “Ulysses” in 2002 for $15 million.