It is a major story in the New York Times, Politico, the New York Post, and the left wing Guardian in Great Britain. It is the most curious of all Barack Obama's problematic relationships and calls into question not only his judgement but the core of his politics.

The story is about William Ayers and Bernadine Dohrn - two members of the radical 1960's terrorist group the Weather Underground  - and the fact that the possible next president of the United States is on a first name basis with a self-confessed bomber of the Pentagon who not only has no regrets for his terrorist action but wishes he could do it all over again.

Larry Rohter and Michael Luo of the New York Times:

On March 6, 1970, a bomb explosion destroyed a Greenwich Village town house, killing three members of the radical Weather Underground and driving other members of the group even deeper into hiding.

On Wednesday night, those events emerged as the focus of a sharp exchange between Senators Hillary Rodham Clinton and Barack Obama at their debate in Philadelphia. Mr. Obama was asked by a moderator, George Stephanopoulos of ABC News, about his relationship with Bill Ayers, a former Weather Underground leader who is now a professor at the University of Illinois at Chicago.

In the early 1970s, the Weathermen, who took their name from a line in a Bob Dylan song, claimed responsibility for bombing the Capitol, the Pentagon, the State Department Building and banks, courthouses and police stations.

Mr. Ayers is listed as a member of the nine-member board of the Woods Fund of Chicago, an offshoot of the Woods Charitable Fund, founded in 1941 by a prominent lawyer and telephone company executive. According to the fund’s Web site, it has focused in recent years on “issues that affected the area’s least advantaged, including welfare reform, affordable housing” and “tax policy as a tool in reducing poverty.”

For a time, Mr. Obama was on the board with Mr. Ayers, though he no longer has a formal association with the group. At the debate, he described Mr. Ayers as “a guy who lives in my neighborhood,” but “not somebody who I exchange ideas from on a regular basis.” Mr. Obama said he was being unjustly linked to “somebody who engaged in detestable acts 40 years ago, when I was 8 years old.”

Wondering whether the three may have crossed paths is not speculation. It is a fact that they have. Ayers, Dohrn, and Obama have appeared together at a number of gatherings and academic events. In November 1997, Ayers and Obama participated in a panel at the University of Chicago entitled Should a child ever be called a “super predator?” to debate “the merits of the juvenile justice system”.

In April 2002, Ayers, Dohrn, and Obama, then an Illinois State Senator, participated together at a conference entitled “Intellectuals: Who Needs Them?” sponsored by The Center for Public Intellectuals and the University of Illinois-Chicago. Ayers and Obama were two of the six members of the “Intellectuals in Times of Crisis” panel.