"We are opposed to this bill," Weizmann said minutes after one of his aides, who sat behind him, leaned forward and spoke to him privately.
The announcement of opposition came after Weizmann read a statement expressing concern over several technical issues he said OPM would have to resolve in order to put in place employee benefits for the same-sex partners of federal workers.
Sen. Joseph Lieberman (I-Conn.), chair of the committee and chief sponsor of the Domestic Partnership Benefits & Obligations Act, said he was pleased that Weizmann's concerns were limited to technical matters that could easily be corrected.
Lieberman said after the hearing that he remains hopeful that the bill will move forward next year.
"This is the first hearing we've ever had on this subject," he said. "We'll be back next year with, I hope, more sponsors, and perhaps we can get it passed."
Lieberman, Sen. Susan Collins (R-Maine), and Sen. Daniel Akaka (D-Hawaii) were the only senators among the 17-member committee who attended the hearing.
Collins and Akaka expressed strong support for the bill, saying they believe it would help the federal government by providing a fair and equitable workplace.
Four other witnesses, including an IBM executive and leaders of the two largest federal employee unions, also expressed strong support for the bill.
Colleen Kelley, president of the National Treasury Employees Union, and Sherri Bracey, program manager for the American Federation of Government Employees, said offering benefits to domestic partners of federal employees would help the government retain qualified workers at a time when many experienced federal employees are nearing retirement.
They also said partner benefits have become widely available from private sector employers, including a majority of the nation's Fortune 500 companies. The two noted that federal agencies must now compete with these companies for highly skilled and experienced workers.
"There has long been a very sound principle that has been embraced on a bipartisan basis," Kelley told the committee. "That principle is that fair and comprehensive employee benefits in our society are best promoted by the federal government operating as a model employer."
Now, she said, the federal government has become a "laggard" on the employee benefits front as more than 53 percent of Fortune 500 companies provide domestic partner benefits for their employees.
"Domestic partner benefits serve as a vital talent development opportunity at the leadership level," said Yvette Burton, global business development executive for IBM. "In a nutshell, it can improve low productivity and morale caused by inequitable workplace practices, thereby creating a positive work environment."
But Weizmann, a former executive with private companies, said he has seen no studies or definitive evidence to show that the absence of domestic partner benefits in the federal workforce has led to a significant loss of employees.
He noted that existing studies show that only 1 percent of employees apply for benefits for their domestic partners, when such benefits are offered in the private sector.
"So few employees use these benefits that it's unlikely that employee retention would be an issue in the federal workforce," he said.
In his testimony, Weizmann also noted that OPM is concerned a provision in the Domestic Partner Benefits & Obligations Act that calls for a signed affidavit to substitute for a marriage certificate used by married employees could lead to fraud.
"Spouse equity benefit determinations frequently rely on state court orders awarding annuity and insurance benefits coverage," he said, in discussing the employee benefits that OPM administers. "There is no analogous provision in the proposed legislation."
Lieberman said his committee would consider this concern and would make revisions at the time of a bill markup.
"We understand that this is something we've got to work on," he said. "It will require education and the presentation of the fact. But I think it's important. It's not only the right thing to do but important to the federal government in terms of attracting and retaining the best employees."
Asked after the hearing whether Republican presidential nominee Sen. John McCain (R-Ariz.), who Lieberman is supporting, has taken a position on the federal partners bill, Lieberman said, "I don't know. I've never talked to him about this, but I will."