'I've never thought of being at the forefront of the campaign and carrying out the co-ordination task. But the situation just developed beyond everybody's expectations. Nobody would have envisaged that things would take such a dramatic turn - the Article 23 legislation and the National People's Congress Standing Committee's interpretation of the Basic Law,' he says.

So the group that was set up two years ago, when the democratic movement was in the doldrums, to organise forums and contact schools, churches and media for the promotion of democracy, became a key player in the co-ordination of the pro-democracy camp in both the District Council and Legislative Council elections. But Professor Cheng says it's time to hand over his post of convenor to someone else when his term ends in December. It was originally scheduled to end in June, but his tenure was extended because of the Legco election.

His work with Power for Democracy has taken up almost all his spare time since he accepted the almost impossible task of co-ordinating and coaching the city's disparate pro-democracy groups in the lead-up to last month's elections. Calling meetings or responding to media inquiries on the latest developments at all hours were just a few of his responsibilities. His motivation for taking on the task, Professor Cheng says, was to shoulder his responsibility as an intellectual at a 'crucial moment' in the city's history.

'We hope to act as a small example, in that there are some people in Hong Kong who are willing to act as volunteers for a worthy cause. After finishing their task, they should be happy to return to their professional work without any demands,' he says.

Except for looking a little weary at times, the soft-spoken professor seldom betrayed his emotions when he was grilled by hordes of reporters over the co-ordination effort - be they sharp questions on the scandals plaguing the Democratic Party or a possible split among the pan-democratic force.

But a few days after the election, he spoke in an uncharacteristically strong tone at a University of Hong Kong forum. He was apparently frustrated with the media coverage of the election, which mainly focused on Cyd Ho Sau-lan's defeat in the Hong Kong Island constituency and the pro-democracy camp getting only 25 out of 60 seats. In a loud voice, Professor Cheng said few in the media had highlighted a strong message: that the record turnout plus the more than 60 per cent of the votes had gone to the pro-democracy camp.

This, he said, was proof to the governments of Hong Kong and the mainland, as well as the rest of the world, that Hong Kong people want democracy and universal suffrage in 2007-08. 'Can you face all the Hong Kong people who have cast their votes if you didn't even mention this fact?' an emotional professor asked an audience of students, lecturers and journalists.

While the mild-mannered professor has rarely shown his emotions, his passion for the cause was evident at this year's July 1 march.

While hundreds of thousands of people marched for democracy, the sweating professor stood under Wan Chai's Canal Road Flyover, greeting the white-clad marchers through a microphone and exhorting them to carry on despite the scorching heat.

Looking back at Power for Democracy's last two election co-ordination efforts, Professor Cheng says: 'In the District Council elections we achieved very good results. And although the Legco results were not that good, overall it's not really that bad. Yes, we've lost a seat in Hong Kong Island, but other than that we fared okay.

'No surprises. No breakthroughs. But no big mistakes either.' Nevertheless, he admits he's a bit disappointed: 'We should have done better.'

Criticism was never far away when the pro-democracy camp decided to co-ordinate their electoral lineup. They faced allegations that supposedly confidential meeting details were being leaked and had their plans disrupted by the sudden decision of former radio host Albert Cheng King-hon to join the race. This pressured fellow pro-democracy candidates as he was outside the camp's co-ordinated electoral lineup.

The defeat of Ms Ho on Hong Kong Island, which many attributed to Democrats Yeung Sum and Martin Lee Chu-ming's last-minute crisis call, further confirmed some people's belief that different political factions had failed to put aside their interests for unity's sake.

But despite all the finger-pointing, Professor Cheng maintains that being able to co-operate 'up to the current standard' is not an easy task.

'From the very beginning, the risk of the co-operation falling through always existed. When we first talked about co-ordination, many people said it was impossible. Now, I think we have at least done something, such as the creation of a joint election platform,' he says.

Professor Cheng says he believes the situation would have been more chaotic if there had been no co-ordination. So, how does he assess their outcome?

'Just as I said in June: 'If the teacher is lax in giving marks, we may have about 50 marks',' he says.

Today, many remain divided over the success of the co-ordination effort, but most of the pro-democracy candidates recognise Professor Cheng's devotion to democratic reform.

Democrat Andrew Cheng Kar-foo, who led the 7.1 United Front - an alliance of seven pro-democracy candidates in New Territories East, where Democrat Wong Sing-chi, who placed fourth on the list, was ousted - praised Professor Cheng's 'spirit of sacrifice' for the democratic cause. 'It wasn't him who was running for election, yet he spent so much of his time calling meetings and negotiating with different political groups,' says Mr Cheng. 'It was much better [for us] to have some co-ordination rather than none.'

Unionist Lee Cheuk-yan said Professor Cheng had tried his best to do the co-ordination work, but given his lack of power and resources, there were many things that were out of his control. 'When things developed in the later stages, everybody was just working for themselves,' Mr Lee says.

The heavy workload undoubtedly affected Professor Cheng's life, especially his leisure time. 'For example, I spent much less time on watching soccer matches, and even the Olympic Games,' he says.

What concerned him the most, nonetheless, was to maintain his standard of teaching and research work in the face of all his extracurricular activities. Though overall he believes he can do so, Professor Cheng says: 'I think the biggest impact on my teaching and research work is that I have read less books than I would have before, it's something that I have to catch up on.'

Having kept a close watch on the city's democratic movement for the past 20 years, the political scientist has felt a change in the social atmosphere. He believes Hong Kong people are more willing to come out to voice their support for democracy than during British colonial times.

The reasons, he says, include the fact that Hong Kong people want to have a say in choosing their leader after enduring the poor governance of the city under Chief Executive Tung Chee-hwa's administration, and also that the middle class has higher expectations of the government than previously.

People's sense of participation have become stronger after the Article 23 controversy. 'After Article 23, people started to think that without democracy, freedom and the rule of law may not get protected,' he says.

But he knows very well that a democratic campaign cannot remain at its climax forever. 'From an academic point of view, a campaign has ups and downs. There will not be any election in the next three years, and the next large-scale march will only occur on July 1 next year at the earliest. How can we maintain people's enthusiasm?'

Pro-democracy campaigners can't always build up people's enthusiasm based on their dissatisfaction with the poor economy and the political situation, he says. 'People were very angry when the Standing Committee of the National People's Congress interpreted the Basic Law in April, that's why so many people joined the July 1 march. But this anger was very difficult to maintain until September's Legco election and beyond.

'But it's hoped that amid the ups and downs there will be more people concerned, and more people becoming convinced that democracy is important,' he says.