"You have to run on a slate and be allied with a philosophical view in order to win," said Marvin C. Foster, former DCC chairman and longtime Cambridge resident.

But sometimes a slate association can backfire on a candidate. Foster noted the case of Barbara Ackerman, whose supporters were so sure she would win that they gave their 1 votes to other slate members, and Ackerman was not elected.

"It's like the old saying goes," said Foster. "Those that live by the slate, die by the slate."

The CCA presently holds four of the nine council seats. The conservative Independents hold another four, and the last belongs to Alfred E. Vellucci, an Independent who often votes with the CCA on housing and social issues.

A new slate, Coalition '85, was formed last January in opposition to the CCA's stand on strong rent control in Cambridge.

Since a candidate only needs 10 percent of the vote to win a seat, the PR system works best for a candidate like anti rent control advocate William J. Walsh, who is running on a protest issue and is backed in part by a specific constituency, Cambridge condo-owners.

The condo-owners are gradually emerging as a new political force, predicted Cambridge pols, but the precarious balance between the CCA and the Independents which has existed for 10 years will likely be maintained.

"The PR system makes for a moderately progressive, stable government," said Truesdell. "Violent alternation in the council isn't in anybody's interest."