It sounds like a campaigning cliche, but in Cambridge, one vote really does count.

Thanks to Cambridge's unique system of proportional representation (PR) voting (please see sidebar), it can take as few as 1,688 votes to get a seat on the City Council, as it did in 1997.

And that's not because of poor turnout, either--that was 1,688 of a total of 17,229 votes.

Candidates are well aware of this as the Nov. 2 elections draw closer, and are trying to cull support from community groups, neighborhoods, and wherever they can find an extra vote.

The way to go, candidates agree, is to target specific groups rather than trying to reach a broad base of citizens.

Seven incumbents, all of whom have at least two terms of experience, are running for reelection Nov. 2, while 17 challengers are also running in a tough race for the nine spots on the council.

Glenn S. Koocher '72, one of the hosts of the Cambridge cable TV political program "Cambridge Inside Out" and a former School Committee member, says that only Cambridge candidates know how to vie for the crucial number one votes.

"It's not like you're mining number- one votes, you're fighting for them," Koocher says.