Members of a Cambridge tenants' group last night attacked a proposal by two liberal City Councillors who say they want to stop homeowners from losing money when they lease their houses temporarily.

Councillors Alice K. Wolf and Francis H. Duehay '55 want to create an exemption in the rent control laws for professors who take sabbatical leaves and others who must leave the city for a year or two at a time. The city now considers homes rented for only a year at a time to be eligible for rent control.

The proposed order would exempt from rent control any home whose owner left it for less than two years because of ill health, a sabbatical leave, or certain other obligations.

Wolf and Duehay, members of the pro-rent control Cambridge Civic Association (CCA), have drawn fire from many of their traditional allies among local community activists, who say the change would create yet another loophole in a code they already consider lax.

Representatives of the Cambridge Tenants Union (CTU) said they oppose any additional exemptions because the city has already allowed many rent-controlled units to return to the open market.

"While it is important to protect tenants' rights, it is also important to protect homeowners, who may want to leave their homes for distinct periods of time," said Wolf, long considered an ally of the CTU.

But CTU Secretary William S. Noble said the proposal could exacerbate what is "close to becoming a scandal," referring to the loss of previously rent-controlled buildings. He estimated that about one-third of the residences initially entrusted to the Rent Control Board have been lost to the unregulated market.

Duehay said he does not believe the exemption will hurt tenants. "It is a very narrow bill designed to respond to specific and legitimate criticism," he said. "It only applies to owner-occupied residences not under rent control." Both Wolf and Duehay emphasized that the exemption would have no effect on existing rent control.

Duehay, who said he supports the CTU's fears about weakening the rent control laws, disagreed with its tactics in this case. "Unless rent control advocates respond positively to legitimate problems in the present system, rent control will disappear from lack of support," he said.

None of the Councillors criticized the proposal at last night's meeting, attended by six of the nine Councillors. Independents Thomas W. Danehy and Walter J. Sullivan Jr. did not attend, nor did CCA Councillor Saundra M. Graham.