In their classic work Transitions from Authoritarian Rule: Tentative Conclusions about Uncertain Democracies, political scientists Guillermo O'Donnell and Philippe Schmitter argue that transitions to democracy often hinge on the interaction among four actors.
These are the hard-liners and soft-liners who belong to the ruling authoritarian regime, and the moderate and radical opposition to the regime.
If the formula applies to Hong Kong, efforts by moderates within the pro-establishment camp and pan-democratic camp to forge a consensus are indispensable for removing hurdles on the path to universal suffrage.
Legislative Council President Jasper Tsang Yok-sing is obviously one of the leading moderates within the pro-establishment camp, whom pan-democrats are looking to if they want to narrow their differences on how to elect the chief executive in 2017.
At a media gathering on September 26, Tsang said the controversy around universal suffrage could be resolved if the central government removed "demons" or unkind thoughts referring to the idea of barring some people from contesting the chief executive election.
Tsang, of the pro-Beijing Democratic Alliance for the Betterment and Progress of Hong Kong, believed a candidate who confronted Beijing would stand a very slim chance of being elected chief executive in 2017.
Tsang, who warned earlier that Beijing would pay a heavy price if a popular pan-democrat was barred from the race, went on to say that whether universal suffrage would be in place for the 2017 chief executive election depended on "a flash of thought" on the part of the central government.
Without naming names, a signed commentary published in pro-Beijing Wen Wei Po on October 2 launched a veiled attack on the Beijing-friendly heavyweight. It criticised the call for Beijing to remove "demons" as being very unfair.
In a commentary published in pro-Beijing Ta Kung Pao on Wednesday, Basic Law Committee member Lau Nai-keung criticised Tsang for urging Beijing to remove "demons" while turning a blind eye to the interference by the United States and Britain in Hong Kong's political reform. British foreign office minister Hugo Swire and US consul general Clifford Hart last month expressed their nation's support for Hong Kong's democratisation, sparking criticism from Beijing.
"People in the pro-establishment camp have no choice, but to unite with the central government in saying no to external forces," Lau wrote.
The criticism levelled against Tsang spoke volumes about the difficulties facing moderates in the pro-establishment camp. Moderates in the pan-democratic camp face a similar plight.
Student-led group Scholarism earlier called for parties to sign a charter listing public nomination - allowing all voters to put forth names for the 2017 chief executive race - as a priority for the fight for "genuine universal suffrage". But Beijing rejected the idea as it is not in line with the Basic Law.
The Democratic Party and the Association for Democracy and People's Livelihood, the moderate pan-democratic groups, came under fire for refusing to sign it.
It is political common sense that the city's constitutional reform can hardly move forward if the rival camps remain poles apart. Whether Hongkongers can elect their leaders by "one man, one vote" in 2017 will depend on whether cool heads in both the pro-establishment and the pan-democratic camps can win over their allies.