Aides to Senator Joseph Lieberman, a Connecticut independent, told the Washington Post Wednesday that the Senate could vote on a bill that would extend some benefits to the same-sex partners of federal employees “within weeks.”

Lieberman is the lead sponsor of the Domestic Partnership Benefits and Obligations Act of 2009 (DPBO) in the Senate. The House version is being backed by openly lesbian Wisconsin Representative Tammy Baldwin. The legislation cleared key committees on both sides of Congress late last year.

Under the bill, the spouses of gay and lesbian federal employees would be eligible for certain benefits currently barred by the Defense of Marriage Act (DOMA), the 1996 law that prohibits federal agencies from recognizing gay unions. DPBO would carve out an exception to the law.

A Congressional Budget Office (CBO) estimate put the cost of the benefits at “$101 million over the 2010-2015 period and $310 million though 2020.”

“CBO assumes that about 0.33 percent of federal employees would choose to register a same-sex domestic partnership if given the opportunity,” the agency said in a report released last week.

Officials said the estimate was based on information gathered from state and local governments which have adopted similar policies. Previous estimates had put the cost of the benefits at $63 million annually.

Lieberman appeared unfazed by the cost increase: “This legislation would cost about two-hundredths of a percent of the federal government's overall costs for the civilian workforce. That is a very small price to pay for the improvements we would see in recruitment, retention and morale.”

Lieberman added that the Office of Personnel Management (OPM) had “committed to provide an offset for the legislation.” Those offsets won't be unveiled until the bill reaches the full Senate.

The bill's single Republican vote out of committee suggests the legislation might face a difficult GOP hurdle in the Senate.

Even Baldwin has conceded that her bill might face difficult opposition from Republicans. She admitted as much earlier at a GLBT leadership conference in San Francisco, where she said several important gay rights bills will need to be tucked inside unrelated bills to clear the Senate's 60-vote threshold.

“I haven't spoken to [Senate Leader Harry Reid], but he is looking through that 60-vote challenge. My sense is he is looking for bills he can attach things to,” Baldwin said. “Senator Reid is committed to finding these vehicles to pass them through.”

During a January town hall style meeting in Tampa, President Barrack Obama reiterated his support for the measure.

“Regardless of your personal opinions, the notion that somebody who's working really hard for 30 years can't take their death benefits and transfer them to the person that they love the most in the world and who has supported them all their lives, that just doesn't seem fair,” Obama said.