THE EERY-BRIGHT LIGHT of the early November moon shines through the railing of a Windsor St. rooftop in South Boston. Down the street to the right, the water in Dorchester Bay lies painfully still, lit by the moon rays. To the right, a row of three-story houses stretches all the way up hill. On almost everyone of them hangs a red sign bearing the words "Leadership, Senator Bulger."

Welcome to politics, South Boston style.

Across town earlier in the day, shoppers and tourists stroll along Newbury St. Some carry shopping bags from expensive boutiques; others chatter in colorful dialects of French and Italian. A blonde woman wearing sunglasses gossips with a man clad in a dark black blazer with slicked back, jet-black hair. Both of them live in Back Bay, but are registered to vote back home--in New York City, of course. Politics Back Bay style.

Both these areas, South Boston and the Back Bay, lie in the 1st Suffolk District, along with the South End and parts of Roxbury and Dorchester. This diverse district is the scene of an unlikely battle, between eight-term incumbent Senate President William Bulger (D-South Boston) and upstart Republican challenger John DeJong, a Back Bay veterinarian.

Bulger has been in office a long time, almost 30 years in the state legislature, and to many observers he bears a more than passing resemblance to the ultra-literate Irish pol Frank Skeffington in Edwin O'Connor's novel The Last Hurrah.

Bulger fancies himself a Classical scholar, a modern day Demosthenes who--like the fictional Skeffington--reads poetry and quotes it liberally in his daily speech.

But unlike O'Connor's character, Bulger doesn't seem to think he's ready for his last hurrah.

In fact, the Senate president sees a bright political future for himself, with the good possibility that his candidate of choice, John R. Silber, will be elected the Bay State's governor.

OVER IN BACK BAY, on the corner of Beacon Street and Mass. Ave., DeJong has other ideas. DeJong's campaign headquarters is easy to spot. Large DeJong--Beat Bulger share the window space with recent newspaper endorsements from the Boston Herald and the Boston Globe.

Inside, a group of campaign workers bustle with activity, as a small white poodle, leashed to a metal bridge table, barks at skateboarders whizzing by the open front door. DeJong, in pleated pants and a blue and white striped shirt, is in the corner of the room giving a stump speech for a local media outlet.

"I'm a veterinarian first, and a candidate, a politician second," he says to the phone interviewer. As he talks, DeJong's dog, a black half golden retriever, half labrador, cautiously approaches wearing a "Beat Bulger" collar around his neck.

"This campaign is about good government," says DeJong. "I think Billy Bulger represents bad government. He does not allow television cameras in the chambers of the state Senate. He will not debate me, and will not even shake my hand. He is arrogant and narrow minded, not someone who respects democracy."

DeJong's hopes rest upon the nationwide anti-incumbent fervor that has already tossed a number of the state's old guard politicians out on their ears this fall. Chief among the villains he singles out for attack are outgoing Gov. Michael S. Dukakis, House Speaker George Keverian and Bulger.

But to DeJong, and Republicans across the Bay State, Bulger is the one pegged as the most autocratic, the most arrogant and the most corrupt. His critics charge that during his years as Senate President, Bulger has climbed to the top of a vast system of patronge and favors, ultimately becoming the most powerful politician in the state.

Bulger is quick to deny these charges, oftenargung that the Senate president's power over hiscolleagues is vastly overrated. And his manysupporters in the state political establishmentare fond of remarking that without Bulger, theentire system might fall apart.