Howard Weizmann, deputy director of the U.S. Office of Personnel Management, told the Senate Committee on Homeland Security and Governmental Affairs today that his office opposes S.2521, which provides domestic partner benefits for federal employees. The issues seemed to be of technical nature related to implementation rather than a principled stance.
Of the 17 senators on the committee headed by Senator Joseph Lieberman, only Lieberman, Senator Susan Collins (R-Maine) and Senator Daniel Akaka (D-Hawaii) were present. Senator Barack Obama is also a member of the committee. As expected, he was on the campaign trail today. It is also being widely reported that Senator John McCain, who is not a member of the committee, hasn't cast a vote in the Senate since April. So I don't read anything into Obama's absence.
Furthermore, he has been a sponsor of the legislation.