A tremendous choice faces voters going to the polls in Cambridge today, with 28 people who represent a wide variety of interests vying for nine seats on the City Council.

Are they opposed to Proposition 1-2-3? Are they endorsed by the good-government Cambridge Civic Association? Did they speak in my dining hall?

But no matter how different those 28 potential councillors seem, they're all Democrats. Like it or not, this is a one-party town. Republicans in Massachusetts-particularly at Harvard--don't get much respect, and neither do their candidates.

And I like it. Because I'm a Democrat.

But when I go home for the summer, I am transplated from this land of Democratic pipe dreams to a town where I am part of a voiceless minority.

Nassau County on Long Island is to Republicans what New York City is to Democrats--a good old boy, down and dirty, no apologies political machine. It is one of the last great political machines in America, living and breathing not in the trenches of urban politics but in the unlikely netherland of the Long Island suburbs.

CLOSE to nothing can stop Nassau County Republicans. Several years ago Nassau's own Boss Tweed, Joseph Margiotta, was convicted and sent to jail. It didn't stop the Republicans. A federal judge recently found that, for years, the party had been forcing government workers to "kickback" 1 percent of their wages to the party. The Republicans have to pay damages, but that hasn't stopped them from completely dominating local government.

This summer, Newsday, Long Island's bible of local politics, ran a cover story outlining the several dozen men (no women) who run Nassau County, listing their outrageous salaries (mostly for part-time jobs) and their potential conflicts of interest. The Republicans will still win again this year.

Of course, you can't blame all this on the Republican party. It's the voters of Nassau County who keep returning the party to office--and on some counts, with good reason.

In general, the quality of life is good, the crime rate is relatively low, and the corruption is not the type that hurts people in an obvious way. It takes a subtler eye to perceive the conflicts of interest, arrogance and non responsiveness that plague the current Republican regime.

Demographically, the reason we Democrats lose is easily explicable. Most Democrats are wealthy commuters who care more about New York City's mayoral race than about who's fixing their streets. The only people who come out to vote are the "townies," local merchants and government workers who depend on local patronage for their livelihood.

The local government blatantly caters to these voters. Town meetings are held on Tuesdays at 10 a.m., when only people who work locally (read Republicans) can attend. Commuters are not going to take a day off of work to keep track of local government.

The continuous re-election of Republicans is usually attributable to a combination of Republican political skill and Democratic ineptitude. Two years ago, the Democrats blew a chance to win the race for town supervisor when incumbent Republican John Kiernan vowed to put a resource recovery plant in a location that was potentially hazardous to the population and the environment. Public opinion in the many areas surrounding the site was viciously anti-Republican.

The Democrat, Ben Zwirn, ran on an anti-incinerator slate and overwhelmingly won the "incinerator district." But he failed to direct any efforts anywhere else in the town. He lost miserably. As usual.

Last summer, I worked full-time as a campaign coordinator for a rag-tag bunch of Democrats, led by Zwirn, who are challenging the Republican leadership in my town, the town of North Hempstead. Having been involved in local Democratic politics for many years, I had become accustomed to the casual nature with which we all treated the futility of our efforts. But this summer, that futility hit home.

Running the campaign for Zwirn and his slate of two town council candidate, one candidate for town clerk, and one woman who was purportedly running for district court judge but refused to campaign, I realized that the vicious Republican cycle is also perpetuated by the quality of candidates the Democrats run.

Zwirm acted neurotically and would pander to almost any group, no matter how politically repulsive. One of the council candidates was a Republican whom we nominated "for balance," taking the nomination away from an intelligent, articulate Democrat who could have run a much better campaign. The other council candidate was the hardest worker of the bunch. A liberal college professor, he is probably the only one on the slate with a chance.

The woman running for town clerk is dynamic, but she ran only after losing the nomination for judge. She's a good campaigner, but her political ambitions are elsewhere. And the woman running for judge is a disagreeable do-nothing, a poor excuse for a candidate.

WITH a slate like this, you ask why we lose?

But it comes as no surprise that the Democrats cannot attract, winning candidates. You either have to be truly devoted to a political cause or a little bit crazy to run a race you cannot possibly win. And because there are few political causes about which to become passionate on Long Island, the candidates are usually a little crazy.

Partially because the candidates were Democrats, and partly because I am an eternal optimist, I took the job running this campaign. I produced seven coherent strategies for candidates to walk through key neighborhoods. I produced several plans for candidates to greet commuters at railroad stations. I made repeated pleas for candidates to communicate with each other. All were ignored.

Frequently, the candidates wouldn't even talk to me. One resented the fact that I was doing too much, because it made her look like she was doing nothing. Zwirn hated me at first because of an old political fight he had with my father. As a result, nothing got done.

The day before I left for Harvard, I put together a make-shift campaign headquarters on a shoestring budget with no telephones. It represented one of the only contributions the Democratic organization would let me make to a backward, lethargic campaign. Democrats had gotten so comfortable with idea of doing nothing and losing comfortably that they were completely surprised by the idea of an active (maybe even winning) campaign.

Being a Democrat in Nassau County might best be defined as the politics of the down and out. We have no inspiring candidates, close to no money and almost no voter support. We are used to losing, and probably wouldn't even know what to do if we won. The result is one-party, closed-door government, running local affairs with no effective opposition.

People ask me, "How can you fight so vehemently against one-party government on Long Island and not decry the same system in Cambridge?"

There is a difference. Among the Democrats of Cambridge, many different interests and political views are represented. It's almost like having the normal range of liberal and conservative candidates--but shifted 10 notches to the left.

On Long Island, politics is run by a monolithic political entity that more resembles the Kremlin than Cambridge City Hall. There is one party line, one party candidate and little room for dissent within that party. The county's party boss is also presiding supervisor of the county's largest town.

In Cambridge, if you disagree with one Democrat, another might win. On Long Island, if you disagree with one Republican, you lose.

LAST week, my absentee ballot came in the mail. I thought about Republican Kiernan and his resource recovery plants and his relatives on the payroll and his 10 a.m. meetings. But then I thought of Zwirn, his panderings, his personal grudges and his neurotic campaigning. What kind of town supervisor would he be?

I marked my ballot. That choice was harder than I thought.