Where have all the Hoppers gone?

"What do we want?" Like all demonstrators, the crowd bellows back an answer. "Painting!" Painting? That seems a rather weak battle cry alongside "world peace" or "jobs", but New York's intellectuals take art seriously. Assembled on Madison Avenue last Friday, their anger is impressive.

The target of this splenetic crowd is the Whitney Museum of American Art. Most of them are artists who practise Realism and many are painters, although a few Realist authors and composers have dropped by to offer moral support. They claim that the Whitney, one of America's leading museums of modern art, has deliberately excluded painting, drawing and sculpture in favour of more "contemporary" media like photography, video and installation art. The demonstration is the latest skirmish in an international battle between Post-Modernism and Realism or figurative art.

The loudspeaker has just been handed to the Realist painter Don Perlis. His next big show will open at the prominent Sindin Gallery next week. It's just across the street from the despised museum that has never exhibited his work. "Modernism is dead," he shouts to the adoring crowd of angry young painters. "The Whitney has dedicated itself to keeping the dead body warm - they are the necrophiliacs of art."

Perlis is especially angry about the 1995 Whitney biennial and its recent choice of the museum's director Lisa Phillips, as the curator for 1997. According to the Whitney, the biennial is "the premier showcase for the most important developments in recent American art". Perlis complains that the past three biennials have failed to deliver that brief because they excluded painting and particularly what he calls "Post-Modern Realism".

"The 1995 biennial had hardly any painting at all, and what the Whitney did exhibit was work by artists who are dead or no longer painting. None of the many fine young painters working today were displayed," says Perlis. "It was a triumph of politics over aesthetics. Lisa Phillips is well known for her antagonism towards painting. Despite the resurgence of painting, especially in Realist forms, 1997 will be a re-run of 1995."

"It's ironic, isn't it?" says the Whitney's deputy director Willard Holmes. We're inside the museum, standing in front of Edward Hopper's Carolina Morning, a painting and a Realist masterpiece. The chants can still be heard, faintly. "Here we have a huge exhibition devoted to Hopper's paintings. We don't have quotas for media and we don't have quotas for style."

So what about the appointment of Lisa Phillips as curator of the 1997 biennial, won't that exacerbate this row? Holmes shrugs. "It's too early to tell. Lisa Phillips has promoted the kind of work that the people outside say has supplanted them. Even so, I think her choices will surprise everybody."

The Whitney has certainly been surprised by the huge public response to the Hopper exhibition. The galleries have been full every day and the museum extended the show by two weeks in response to public demand. People stand and stare at Hopper's moody, vibrant paintings for minutes on end and the Realists outside think that that proves a point.

"This is what people want to see," says demonstration organiser Steven Asal. "Realist painting always draws the biggest crowds. The problem is that 50 years from now this generation won't have its own Hopper to create a sell-out show. Without the validation of major museums like the Whitney, painting will die and many young artists will abandon painting."

"I often say that painting is dead," says ultra-traditional art critic Brian Sewell, who sees British art trapped in the same Modernist rut. "I don't mean that there are no painters, just that in a gallery like the Tate there are no signs of life." Like the Whitney protesters, Sewell smells a conspiracy against painting. "A little group of 25 people run the art world in this country. They sit on the Arts Council and dominate its policies and they will let nobody else in. Consequently, painters have nowhere to exhibit."

The secretary of the Royal Academy, Piers Rodgers, rejects Sewell's thesis with a sniff. "I think things are more finely balanced. The London scene is hugely varied. Expressionist painting was popular in the Eighties. I think that now we are seeing a new appreciation of abstract art and maybe in that sense Europe is ahead of the US."

Sewell remains doubtful. He cites the Tate's "Rites of Passage" exhibition as an example of the influence of the "Serota Tendency" after the gallery's director Nicholas Serota. "The subtitle for the exhibition is 'Art for the end of the century'. The clear intent is to suggest that the exhibition represents the art that will carry us into the next millennium. But they have not chosen a single painting or sculpture."

Serota was unavailable for comment on Friday, but the Tate's press officer, Adrian Hardwick, denied that the gallery had excluded painting from any exhibition for anything other than aesthetic reasons. The Tate's attitude enrages Brian Sewell. "The power and the patronage of the British art world is formidable and exclusive of painting, but they are also cowards. They won't even engage their opponents in debate."

With the New York painters' demonstration put in an international context, their protest seems a little less absurd. But this is not the first time the Whitney has been caught out for its role in a global conspiracy against painting. "I am deeply disturbed by the slight representation of painting in this year's annual show," wrote Hopper himself in 1960, in a letter signed by 22 prominent artists of the day. Hopper took to the picket lines that autumn as over 500 people joined a protest outside the Whitney.

At this 1995 demonstration, an artist hands out what looks like a photograph of a young woman in a black evening dress. Laurel Stern's painting is hyper-Realist, but fascinating. Close examination of Evening reveals ironic touches; the woman has one earring missing. Her hands hang down in front of her, folded into each other just below her pelvis. The painting demands that you keep looking, to try and find the woman's secrets. The technical execution is excellent and reminiscent of John Singer Sergeant at his best.

"The Whitney uses words like 'retrograde' or 'regressive' to keep us out," says 32-year-old Stern. "If you don't share their Modernist aesthetics you're some kind of illustrator hack." Nearby, the New York art critic Hilton Kramer nods his agreement. "Radical innovation is easier than painting a marvellous picture," he says. "Most of the objects in the Whitney biennial can be encompassed in about 40 seconds."

Any political issue in New York is bound to involve race. One Whitney insider said she thought the Realists outside were "white bourgeoisie", representative of a race and class that has had its day. "Yeah right," says Perlis. "So I guess that makes Hopper some kind of racist. Look, the Whitney is not going to win this one by bringing in some spurious politics. The biennial should be like the Royal Academy's Summer Exhibition. If a living artist realises his or her vision with exceptional talent, their work should be exhibited."

The autumn sun shines out of a china-blue sky, the Madison Avenue traffic crawls to a chorus of cab horns and the chants start again. "Whitney sucks! Whitney sucks!" The Whitney says the demonstration is unlikely to bring a change of policy but it will keep the controversy alive. The painters don blindfolds and surround a blind justice with unbalanced scales. "This is about the future," says one. "We're fighting for the soul of American art and the right to work."