Protesters raise Hong Kong colonial flags during a July 1 march in a downtown street at an annual pro-democracy protest in Hong Kong. (Vincent Yu/AP)

After a decade of negotiations, sociology professor Chan Kin-Man realized the Chinese government was not going to grant Hong Kong genuine democracy. Not without a struggle, anyway.

So with another academic and a Baptist minister, Chan has threatened to organize a sit-in for democracy in Hong Kong’s business district.

The threat has resulted in one of the biggest political tempests in Hong Kong in years. The Chinese government has warned darkly of “chaos,” while its media have said the mild-mannered trio and their supporters risk becoming an “enemy of the state.” Hong Kong’s business elite are so alarmed at the possibility of unrest that they have organized a rival movement.

All of this in reaction to a demonstration that is not supposed to take place until next year.

“After 10 years, I know so well that unless we generate enough pressure, Beijing won’t give us universal suffrage,” said Chan, adding that civil disobedience would be a last resort if negotiations fail. The campaign he is helping to lead, known as Occupy Central, is modeled on the nonviolent protest of Mahatma Gandhi and Martin Luther King Jr.

The campaign reflects a growing belief that Hong Kong’s political system has become dysfunctional. Under the terms of the former colony’s 1997 handover from British rule and the “one country, two systems” model, Beijing promised to grant Hong Kong “a high degree of autonomy.” A decade later, China’s Communist Party pledged that Hong Kong’s political leader, the chief executive, could be chosen through universal suffrage starting in 2017.

The party, however, would retain veto power over who could stand in any such election, through a nominating committee packed with loyalists.

The island’s current chief executive, Leung Chun-ying, was effectively chosen by Beijing and is widely perceived as putting the Chinese government’s interests ahead of those of his people.

Now the Occupy Central campaign — which is separate from the global Occupy movement — has threatened to bring 10,000 people to indefinitely block the streets from July onward if Beijing refuses to allow a free nomination process.

“We have to show them we are serious to make them talk to us,” Chan said.

Chan said he is worried that if electoral reforms do not come, young people will become more radicalized and the middle class will emigrate in greater numbers. The growing frustration of young people was obvious last year when they led protests against a pro-China education syllabus .

Chan is joined by Benny Tai, a constitutional law expert who thought up the idea of the demonstration, and the Rev. Chu Yiu-Ming, who grew up in China before fleeing to Hong Kong and, in 1989, helping Tiananmen Square activists escape China.

Most Hong Kongers accept that the territory belongs with China, but many also yearn for a democracy denied them first under British rule and now under the Chinese.

In 1989, in the wake of the crackdown on the Tiananmen Square protests, a million people, nearly a fifth of the population, took to the streets of Hong Kong in sympathy. In 2003, half a million marched against a planned anti-subversion law that could have curtailed freedom of speech.

Only a directly elected chief executive would have the mandate to govern effectively, many people say; even pro-Beijing figures such as Jasper Tsang, president of Hong Kong’s parliament, have warned that the territory will become “ungovernable” if universal suffrage is not introduced in 2017.

But Hong Kongers are pragmatic people for whom civil liberties are important but stability and economic growth are at least as critical. Most want to avoid confrontation with Beijing; support for Occupy Central was pegged at just 25 percent in a recent poll . Tai said that only 1,500 people have signed up to support the movement and that only half of them have agreed to join the sit-in, although he says it is still very early.

But that has not stopped the trio from facing daily vilification. The business community, which benefits enormously from the status quo, has formed a rival movement, the Silent Majority , led by a TV and radio host and entrepreneur, Robert Chow, to mobilize people against the protest.

In an interview in the exclusive Hong Kong Jockey Club, Chow said a sit-in protest could paralyze the territory’s streets, send the stock market crashing and occupy the police to such an extent that looters would run riot elsewhere. The Chinese authorities, he warned, could be forced to call out troops.

He says peace-loving Hong Kongers need to stand up against the “aggressive few” who seem intent on causing problems. “I am not against democracy, but I just don’t want chaos,” he said.

Many people accuse Chow of scaremongering but say that arrests and then further protests remain a distinct possibility.

The Chinese government has been engaged in a clampdown on political freedom across the rest of the nation since Xi Jinping took over as president this year.

When the United States and Britain recently underlined their support for a transition to “genuine” democracy and universal suffrage in Hong Kong, Beijing slammed them for irresponsible “interference in Hong Kong’s internal affairs.” The U.S. and British comments did not explicitly support Occupy Central but were seen as validating its goals.

Hong Kong University law professor Michael Davis said a compromise can still be struck, perhaps allowing one “democratic” candidate to run in 2017 but granting Beijing some power to veto more radical figures. But the chances of a deal seemed to recede after Chu traveled to Taiwan last month to meet a pro-independence activist there, supposedly to seek advice on staging peaceful protests. Chinese media warned that the movement was “risking a dangerous act of secession.”

“If Beijing’s tactic in dealing with Occupy Central is to attack, vilify and escalate the Cultural Revolution-style political campaign, this may increase support for Occupy Central,” Davis said. “But if Beijing is sensitive to Hong Kong people’s concerns, they could deflect a lot of this.”

Regina Ip, a pro-Beijing legislator, said Occupy’s supporters are being unnecessarily provocative. “There are many definitions of democracy, but we can’t have democracy where our people have the entire say in choosing our leaders and we cut Beijing out of the picture,” she said.

Tai and others say Beijing has little to fear from elections. “Hong Kong people are very pragmatic,” Tai said. “They know that no one who has bad relations with China will be able to govern us, so the chances of someone getting elected who doesn’t get on with China are very small.”

Nevertheless, that calculation requires a leap of faith for a Communist Party that has never faced the judgment of an electorate,and may fear that the demands for democracy could spread to the mainland.

“Giving up control is not something Chinese Communists are used to doing,” said pro-democracy legislator Charles Mok. “This is a mental block they have to overcome. Are they going to trust us in running ourselves?”

Zhang Jie contributed to this report.