NEW YORK -- In a sparsely furnished basement office across the street from a loading dock, Catharine Cary, a Washington marketing consultant turned Manhattan community activist, prepares to do battle with Donald J. Trump.

Her target is Trump City, the biggest project conceived by the billionaire developer, whom no one has ever accused of thinking small. On a 76-acre tract along the Hudson River, Trump wants to erect the world's tallest building -- a 150-story office tower that would include a luxury hotel -- as well as three other office buildings, a regional shopping mall and 7,600 apartments.

"It will look kind of gargantuan," said Cary, 28, executive director of a community group called Westpride. "It's really just more than the neighborhood can handle."

There was a time, a few short years ago, when such a project probably would have been approved with little fuss. City officials took a dollars-and-cents approach to megadevelopments such as Trump City, which its backers say would generate $150 million a year in city taxes, $650 million a year in retail sales and thousands of construction jobs.

Trump has been as caustic toward Westpride as in his celebrated divorce battle with his wife, Ivana.

"Those people fight for the sake of fighting. . . . Selfishly, they like what they have and don't want to give it to anybody else," he told Playboy magazine. "We need another Rockefeller Center, especially now that Mitsubishi has bought most of the one we had."

Although preliminary approval of Trump City is expected soon, the project's path has been slowed by red tape and a backlash against overdevelopment that began to gather force in the late 1980s. Neighborhood opposition has blocked other major projects, from publisher Mortimer Zuckerman's proposed skyscraper at Columbus Circle to a huge condominium development at Brighton Beach in Brooklyn.

Such sentiments are particularly strong on Manhattan's Upper West Side, whose stately, mid-rise apartment buildings along Broadway and Central Park West have long been home to prominent artists, writers and entertainers. Many of them, including television commentator Bill Moyers, author E.L. Doctorow, actors Tony Randall and Christopher Reeve and cartoonist Jules Feiffer, are backing Westpride.

Robert Caro, Pulitzer Prize-winning biographer of master builder Robert Moses, has written a Westpride flyer describing the Trump plan as "a phalanx of monstrous skyscrapers, looming as an enormous wall against the western sky, looming over the West Side, crushing human scale out of a vital, lively neighborhood."

Judith Rossner, author of "Looking for Mr. Goodbar," has held 8 a.m. Westpride meetings at her home. "The West Side is very much my town," she said. "This project is a huge, ugly combination of the worst of a shopping center and an industrial park. It's just ghastly. You're talking about a radical change in the neighborhood I love."

Such celebrity involvement has helped Westpride raise $200,000 a year. Three dozen artists donated works for an auction last December that raised $80,000, and a benefit concert last year featuring violinist Itzhak Perlman netted $40,000.

"We had to have financial and political clout in order to mount an effective opposition," said architect Steven Robinson, who helped to found Westpride in 1986 with $1,000 donations from a dozen families. "We really did not want to form a group that would run through the street waving banners saying, 'This building's too big.' "

Anthony Gliedman, a Trump vice president and former city housing commissioner, brushes aside objections to the $4 billion project as "misinformation." Trump City "is going to be a wonderful place to be," he said. "We really believe it will be a tourist attraction. It'll help 98 percent of the city.

"I live in Flatbush," Gliedman said in his Trump Tower office. "If someone were going to build a large project there, I would be nervous." But he said critics do not have enough information about Trump City and have played down its benefits, such as 19 acres of parks and public space that would include a 13-block waterfront promenade.

Gliedman, 47, also stressed the prestige of recapturing the title that New York has lost to Sears Tower in Chicago. "Donald is a New Yorker; he really believes we should have the world's tallest building if we're going to be the premier city in the Western world," he said.

The waterfront site, from 59th to 72nd streets, is an abandoned Penn Central rail yard that several builders have tried to develop since the 1960s. Trump originally tried to lure NBC to what he called Television City and got into a name-calling fight with then-Mayor Edward I. Koch (D) when he demanded city tax breaks for the project, rechristened after the network decided to stay in Rockefeller Center.

Cary, whose staff consists of an unpaid college intern, has used the Freedom of Information Act to uncover data about the project. She also has hired economists, engineers and lawyers to gauge its potential impact, right down to the percentage of non-Manhattan residents who would shop at Trump stores.

"We try to do the same kind of analysis of air quality, traffic, sewage and economic development that the Trump Organization does," she said. "This project would be twice as dense as the area around it."

With 27,000 people projected to live or work in Trump City, Westpride says the development would overburden mass transit, sewage treatment, schools and other vital services. The shopping mall, which Trump expects to pull customers from the New Jersey suburbs, would choke the neighborhood with traffic and exacerbate air pollution in a city whose smog levels exceed federal standards, the group says.

Cary ridiculed plans for the waterfront park, saying it would be so noisy and windblown that "conversation would be impossible without raised voices." Pollution from office buildings and the elevated West Side Highway would render the park's air "unbreathable," she said.

Westpride depicts the 150-story building as a monstrous intrusion that would cast shadows on Central Park and a quarter-mile into New Jersey.

Gliedman offers a far rosier scenario. The park, he said, would be quiet and pollution-free. Much of the traffic would bypass the neighborhood through a new highway off-ramp, he said, while Trump, as part of the deal, would renovate the dilapidated Broadway subway station at 72nd Street.

Gliedman also said the regional shopping center is not the behemoth described by critics but, at 800,000 square feet, about half the size of Macy's department store, the world's largest.

While many critics thought the original futuristic design by architect Helmut Jahn "could be equally in place on the moon as in Manhattan," Gliedman said, a new layout by Alexander Cooper is slightly smaller and maintains the city's street grid.

"The idea is to make this part of the fabric of the city," Gliedman said.

But the opposition is settling in for a long siege against a project that would force people on the Upper West Side to "live in Donald Trump's shadow," as former parks commissioner Henry Stern once put it. One Westpride poster features a thicket of skyscrapers at dusk with the inscription: "Enjoy the Sunset over the Hudson -- While You Can."