HONG KONG (BLOOMBERG/CHINA DAILY/ASIA NEWS NETWORK) - The Hong Kong legislature is set to debate the single largest democratic reform in the city's history on Wednesday as a handful of lawmakers hold in their hands the fate of more than three decades of political wrangling over the issue of giving residents the right to vote for their leader.

The motion to amend the Basic Law and grant universal suffrage under a framework endorsed by the Standing Committee of the National People's Congress could come to a vote in the evening at the earliest, though three days have been set aside for speeches, questions and answers.

The government is seeking to secure the two-thirds majority vote needed to alter Hong Kong's mini-Constitution.

If the proposal is passed, candidates for the role of chief executive will be vetted by a 1,200-strong committee made up of representatives from different economic, political and social sectors who may support multiple candidates and will recommend and nominate two or three candidates.

Candidates who secure support from at least half the nominating committee will then face the city's registered voters.

With 42 votes out of a total of 70 all but spoken for in favour of the package, a margin of five votes is all that is needed to grant the 3.5 million registered voters a say in who runs the city from 2017.

Anything less and the opposition's campaign to veto the proposal despite overwhelming support for it will succeed, retaining the status quo and leaving the group of 1,200 appointees who made up the last election committee in 2012 to choose a chief executive.

Ms Carrie Lam, the chief secretary for administration, has warned that defeat for the proposal will mean the 2012 election method will be retained for the 2017 election.

Defeat will set off a domino effect eliminating "the chance of forming the Legislative Council by universal suffrage in 2020. The result is that we may only have the chance to achieve universal suffrage for the Chief Executive election in 2022 at the earliest".

Ms Lam said failure to move forward on the reform plan will compel the administration to focus on economic issues in the remaining two years of its term, as Hong Kong's competitiveness faces rising pressure from regional rivals.

Lawmakers on both sides of the debate consider it likely the plan will be rejected as Chief Executive Leung Chun Ying needs at least four of the 27 pro-democratic lawmakers to secure passage.

Opponents say the proposal is designed to produce a pro-China candidate and fails to extend the universal suffrage mooted in the city's de facto Constitution.

Failure to pass the plan would deepen a divide in the legislature that has stalled legislation and delayed this year's budget by six weeks.

Passing it could trigger further unrest with some leaders of last year's protests pledging a return to the streets, although recent rallies have been small in size.

As legislators prepare to vote, some in Hong Kong's international business community fret that too little has been done to address the sense of disenfranchisement that brought more than 100,000 protesters out at the height of the Occupy Central movement.

"People have developed a perception that the system is biased against the small guy and in favor of the big guy and that didn't used to be the case," said Mr Paul Serfaty, a director of Asian Capital Partners Group, an investment bank that specialises in mergers and acquisitions.

Some of Hong Kong's middle class have been shut out of the city's economic gains as rising asset prices made Hong Kong home to the highest concentration of multimillionaires of any city on earth.

Around half of Hong Kong workers earn less than HK$14,000 (S$2,400) a month, and 7.7 per cent less than HK$5,000, according to government figures.

Almost half of the population lives in public or subsidized housing.

"The risk for Hong Kong is that it enters a slow period of stagnation, barely noticed year to year, but betraying its potential," said Mr Serfaty, a Hong Kong resident since 1988.

Tensions have been mounting in the run-up to the vote. The police stationed 200 officers inside the Legislative Council building on Wednesday to deter potential protesters, the South China Morning Post reported.

The anti-graft agency said on Monday it was investigating allegations by a legislator that he was offered a bribe to support the electoral package.

Pro-democracy lawmaker Leung "Long Hair" Kwok-hung said he was offered HK$100 million for his vote.

He later said he exaggerated the sum to get attention, though the bribe offer was true, according to comments he made to the South China Morning Post.

Ten people were also arrested in connection with a plot to make explosives, with at least one claiming to be a member of a "local radical group", the police said. The suspects had masks of Guy Fawkes, who led a failed plot to blow up the English parliament in 1605 and is a symbol of anti-establishment protesters.

More than 7,000 police will be deployed during the Bill vote to prevent any new occupation, and will be prepared to use tear gas and pepper spray if demonstrations turn violent, the South China Morning Post reported on June 2.

The city remains split over the plan. According to a daily tracking poll conducted by three local universities, 44.9 per cent supported the measure as of June 12, with 40.9 per cent opposing it.

Even if pro-democratic lawmakers succeed in blocking the plan - which would mean the 2017 chief executive is again selected by a committee rather than voters - tensions in the legislature are likely to persist given the lawmakers say Mr Leung lacks a popular mandate.

That would risk slowing Mr Leung's agenda further. In February, he blamed the pan-democratic camp for filibustering to hinder pending legislation.

Ms Regina Ip - chairman of the New People's Party, which backs the plan - predicted opposition lawmakers would increase delaying tactics that held up this year's budget, complicating the rest of Mr Leung's five-year term.

"It will be very difficult for CY, but not impossible," said Dr Wong Yiu Chung, head of the department of political science at Lingnan University in Hong Kong. "The pan-democrats can filibuster, but in the end the chairman of LegCo can cut them off."