Reitwiesner, the researcher, declined to be interviewed for this article. "I'll let my Web page [] speak for itself," he said in an e-mail. The Obama report contains a disclaimer that appears on all of Reitwiesner's work: "The following material ... should not be considered either exhaustive or authoritative, but rather as a first draft."

Genealogical experts who reviewed the Obama family tree at the request of The Sun would not vouch for its findings.

Most of the historical entries lack citations of authenticating source material, such as birth and death certificates or marriage licenses, said Barbara Vines Little, past president of the National Genealogical Society in Virginia, adding that "he has nothing here that I can see that would allow you to make any logical link."

"You just can't casually throw some documents together and make a sophisticated analysis," said Tony Burroughs, author of Black Roots: A Beginners Guide to Tracing the African American Family Tree and a consultant on a project by the New York Daily News that found that relatives of former Sen. Strom Thurmond appear to have owned the ancestors of civil rights activist the Rev. Al Sharpton.

But Roberts, the New England scholar, collaborated with Reitwiesner on a 1984 book about the American roots of Princess Diana, and calls him "exceptionally bright" and "quite a good researcher."

The online Obama family tree, Roberts said, is the work of "an informal team of genealogists" who specialize in Internet-based research and post their findings to test their validity.

"When you are gathering up things from the Internet, you can get fantastical - by that I mean wild and unbelievable - connections," Roberts said. "Many of them will fall; only a few of them will hold up. But some absolutely extraordinary things do hold up."

Assisting in the Obama research was Christopher Challender Child, a genealogist at the New England Historic Genealogical Society, who said that Reitwiesner culled fragments from a variety of sources. "There's a limit to what you can verify without a lot of money," Child said. "But from what I see, the line looks pretty good."

For some, the records may underscore Obama's unique racial heritage as a presidential candidate.

Author and essayist Debra J. Dickerson wrote in a January article that she had previously refrained from opining about the senator because "I didn't have the heart (or the stomach) to point out the obvious: Obama isn't black."

" 'Black,' in our political and social reality, means those descended from West African slaves," Dickerson said.

Walters, who was deputy campaign manager for Jesse Jackson in 1984 and the author of Black Presidential Politics in America, agreed that questions raised by Dickerson and others "is an important debate."

"What people are really asking is, 'Can I trust this guy? Do I have confidence in this guy? Does he understand my situation, and therefore [is he] able to take my issues into the political system?'" Walters said.