Two years ago, Cambridge was the site of a City Council race that, while often bitter, was hardly revolutionary.

All nine members of the council ran for reelection. All nine won.

Such results are commonplace in Cambridge, which uses a system of proportional representation (PR) that virtually assures re-election for incumbents. In fact, many city residents joke about the real meaning of PR--perpetual representation, they dub it.

This November's election, however, is destined to be different. For the first time in more than 25 years, three city councillors will not seek reelection, paving the way for one of the most dramatic council races in the nearly 50-year history of PR.

The three vacancies leave the race wide open. The good-government Cambridge Civic Association--which has commanded a four-member minority on the council since the early 1970s--and other liberal groups could make up a progressive majority on the council come next November. But given the edge PR seems to give incumbents, the CCA is facing an uphill battle.

Two outgoing councillors--Saundra Graham and David E. Sullivan--are longtime members of the CCA, and the third--Mayor Alfred E. Vellucci--is a fierce Independent who is often the council's swing vote. Although CCA members have made up a minority on the council, cooperation with the mayor on rent control and affordable housing issues has allowed them to push through their program in several areas. Vellucci's departure could threaten this balance.

And a fledgling progressive group--the "grassroots" Working Committee for a Cambridge Rainbow--is adding a new dimension to this year's race.

"We're trying to reach those constituencies that have not been reached by the various other political groups," says Rainbow spokesperson Janet Murray.

The Rainbow sports a political platform that in some ways echoes the CCA's but in other ways goes beyond it. In particular, its platform calls for reform in the basic structure of Cambridge government, which gives nearly all executive power to a council-appointed city manager.

The two groups agree on many of the issues facing the city. Both favor maintaining the city's rent control system and oppose Proposition 1-2-3, a ballot referendum that would allow tenants in some rent-controlled housing to buy their apartments. Both also support strict limits on development.

In fact, voters are likely to find the difference between the Coalition and CCA largely rhetorical--especially since all Rainbow candidates are also CCA-endorsed candidates.

Imitation or the Real Thing?

Voters may also recognize some unusual similarities between candidates and current council members because many council hopefuls are modeling themselves after one or more of the departing progressives.

Others frown on this technique.

"I have great respect for the people who are leaving, but I ran in the last race--unlike a lot of other candidates who are billing themselves as successors or whatever," says CCA-candidate Jonathan S. Myers, who came within 200 votes of winning a council seat in the last race. "I didn't bill myself as replications of any of those people then, nor am I doing that now."