Without the benefit of any historical precedent to aid them, the two minority parties now represented on New Haven’s Board of Aldermen are struggling to choose a single leader before the legislative body begins its business this month.

Following an election in which the Green Party won an unprecedented two seats on the 30-member city council, the political organization founded by Ralph Nader now has as much voting power as the city’s Republicans, who have for decades been the board’s sole minority.

And despite their historically disparate ideologies, the two parties must find a way to share power: the board’s rules only allow for a single minority leader.

Although the minority leader will have relatively little power compared with the board’s 26 Democrats, the position remains important because he or she will sit on a high-level committee that has oversight of the city’s legal affairs.

The four aldermen will also have to share representation in the legislative process because board President Jorge Perez said he will appoint only a single minority-party alderman to all but one of the body’s committees.

Ward 25 Alderwoman Nancy Ahern was minority leader before this year’s Green Party upset and has maintained that she should continue to serve in the role.

“My position, as has already been expressed, is that the representatives of the major parties should be the leadership on the Board of Aldermen,” she said.

Ahern asked the city’s top lawyer, Corporation Counsel Thomas Ude, to determine if there was any legal precedent that might yield a solution to the problem.

Ude discovered there was none.

“It remains a political question,” he said. “It goes back to the minority.”

While he did not find any precedent in New Haven history — or any local, state or federal laws that govern situations like this one — Ude said there are situations in countries with parliamentary governments where several minority parties have formed coalitions to become a majority.

“But I don’t know about parties that are not in the majority forming coalitions to become a minority,” he added.

John Halle, the Yale music professor who leads the Greens from his seat in Ward 9, said that, no matter how the situation is resolved, he did not think the decision would have a significant effect on the city’s political business.

“There’s a tendency to look at this in terms of a horse race,” he said. “What’s important is who gets to exert influence, not just who’s up and who’s down. It’s relatively small potatoes in terms of real politics.”

But Halle said he did not necessarily agree with Ahern’s assertion.

“The fact is, there’s not a place anywhere in the charter, or in state law, or in national law, that says what we should do in a situation like this,” he said. “There is no basis for either Nancy or me to have this position. Nancy is operating under the assumption that she will retain her position because the Republicans are the established party.”

Perez said he would not be surprised if Ahern retained her position, although he added he was merely speculating.

“I don’t know what’s going to happen, because I’m not part of their caucus,” he said. “I’ll be very surprised that Nancy won’t be minority leader, given her experience. But I personally feel that I can work with either one, and I don’t want to influence the decision in any way. I feel it would be inappropriate to do that.”

Perez, who has the exclusive authority to make committee assignments, said he will make them as he has always done.

“I’ll take requests for committee assignments — from every alderman, if need be,” he said. “Then I’ll come up with the lists. That’s what I’m inclined to do.”

Perez said he plans to assign one minority-party alderman to each regular committee and one from each party to the powerful Finance Committee.

For the moment, which aldermen will be assigned to which committees remains a mystery.

Halle said he called a meeting with Ahern to discuss the matter.

“But I can’t say that the Republicans seemed to be particularly open to negotiating,” he said. “[Perez] is fair. It’s hard to tell what basis he will use, though.”

Ahern said she plans to submit her requests within the week.

“I understand, and I think that it’s appropriate, that there will be one non-Democrat on each committee,” she said. “And I’m sure that [Perez] will accommodate our preferences as far as is possible.”