Following the links on John Hinderaker's post on Obama's apparent affiliation with the Democratic Socialists of America/New Party leads you to DSA newsletters that make several references to Obama between 1995—2004. According to the newsletters: 

 

— Obama participated in the 1996 Young Democratic Socialists conference. The newsletter praised Obama's speech at the gathering, stating that what Obama had to say was "well within the mainstream" of European socialist theory.

 

— The suggested theme for the 2004 Annual Eugene V. Debs Dinner was Dump Bush and Elect Obama

 

— The Sept.-Oct. 1995 newsletter notes that Barack Obama, chief of staff to state senator Alice Palmer (whom Obama succeeded), urged New Party members to participate in Obama's voter registration drive.

 

Obama is identified as a member of the New Party. There are photos of Obama with other New Party members also.

 

John states that the info was scrubbed from the New Party websites this summer and the Obama campaign has denied an affiliation with the organizations. John, however, was able to find archived newsletters at the Internet Archive Organization.