More than two months after proposing new travel and ethics rules, House Democrats continue to explore ways to extend certain travel perks to the same-sex domestic partners of gay Members and staffers.

“We’re trying to work it out, so there’s fairness [with married Members],” said Rep. Barney Frank (D-Mass.), chairman of House Financial Services Committee and one of the chamber’s two openly gay Members.

An official with a conservative group said any attempt to extend travel benefits to the partners of gay Members and staffers could be challenged.

“This is the federal government recognizing same-sex partnerships,” said Tom McClusky, vice president of government affairs for the conservative Family Research Council.

Hill sources, outside lawyers and interest groups all suggest that the layers upon layers of confusing language in Congressional rules outlining sanctioned relationships and official and private trips make it difficult to speak generally about what is and is not allowed.

“The rules aren’t entirely clear,” said C. Simon Davidson, a Washington, D.C.-area lawyer and expert on Congressional ethics.

Still, a major fault line exists, said Davidson, who also is a Roll Call contributing writer. The rules currently on the books, he said, segregate Member and staff travel into two primary categories: travel that is related to official duties and paid for by the government, and travel that is related to official duties and paid for by a private organization.

When an outside group picks up the bill for official travel, Davidson said, House rules outline that Members and staffers may bring along an undefined family member — a holdover from the previous Congress, which had altered the classification from “child or spouse” roughly two years ago.

“You can [be reimbursed for] travel that is connected to official duties,” Davidson said. “It used to be a spouse or child, but now it’s just ‘relative.’”

Whether the unmarried domestic partner of a gay or heterosexual Member qualifies as a legal “relative,” according to Davidson, is a different discussion altogether.

As he wrote in Roll Call on March 5:

“The rule does not define ‘relative’ … moreover, the ethics committee has not published a definition or relevant guidance. … In the absence of a formal definition, you do have an argument that your domestic partner qualifies as a relative. In D.C., legally registered domestic partners are afforded many of the same legal rights afforded to married couples, including, for example, health insurance, testimonial privileges, alimony and child support. Therefore, you could argue that domestic partners should qualify as ‘relatives.’ However, the ethics committee is not necessarily bound by the D.C. registration law.”

Davidson said in an interview Wednesday that one way Democrats could allow domestic partners to travel on private trips would be to amend the rule through regular order or unanimous consent — a route House Republicans have been particularly critical of in recent weeks. Davidson also said Democrats simply could provide a list of family members that could join Members and staffers on privately sponsored travel.

“They don’t currently define relative, so they could just say our interpretation includes domestic partners,” he said.

House Democrats declined to comment at length on ongoing discussions. But a House leadership aide said that barring future developments, such requests will be handled by the House Committee on Standards of Official Conduct.

“Currently, the ethics committee reviews situations in which there is no legal status recognized by the federal government between two unrelated adults,” the aide said. “This applies to unmarried heterosexual couples as well.”

Frank stressed that benefits only would be extended in cases where a relationship has some kind of legal standing.

“It has to be a recognized relationship,” he said.

Regarding official trips directly paid for by the government, House rules now stipulate that the federal government will pay the way for Members’ spouses who travel overseas on official business, according to a Democratic leadership aide. Those benefits theoretically could be extended for domestic trips, the aide said, but such requests rarely — if ever— are made.

While the federal government will pay spouses’ air travel and other expenses no-questions-asked, the aide said, Members may try to seek an ethics waiver for a non-relative who wishes to travel with the Member or staffers on the government’s dime. Those decisions will be made, the aide said, on a case-by-case basis and at the discretion of Speaker Nancy Pelosi (D-Calif.).

Although future decisions could potentially affect untold numbers of House staffers, Frank and Rep. Tammy Baldwin (D-Wis.) are the chamber’s only two openly gay Members.

McClusky, of the Family Research Council, said House leaders could put themselves in legal or political jeopardy if they decide to extend travel benefits to the partners of gay Members and staffers.

“If it doesn’t go against the law of the Defense of Marriage Act, it goes against the meaning behind it — and I would expect challenges based on DOMA,” he said. “This is just the first salvo in a much larger agenda that’s going to include [hate] crimes, the employment non-discrimination act and ‘Don’t Ask, Don’t tell.’”