Political scientists cited the Civic Party's "over-ambitious" strategy as well as pan-democratic infighting - notably People Power's attack on the Democratic Party and the Association for Democracy and People's Livelihood for supporting the 2010 electoral reforms.

The pan-democrats' share of the geographical constituency vote dipped by 1.5 percentage points from 2008, meaning the usual 60/40 split between pan-democrats and the Beijing-loyalist camp did not hold.

The margin between the two camps was especially narrow in the five new "super seats" in the functional constituency for district councils. The three pan-democratic slates gained 50.7 per cent of the 1.59 million votes cast, while Lau Kong-wah, his allies on two Beijing-loyalist slates and independent Pamela Peck Wan-kam took 49.3 per cent.

"The pan-democrats should no longer hope for the 60/40 split. They should review their strategy instead," said political pundit Dr James Sung Lap-kung, of City University's School of Continuing and Professional Education.

Sung also blamed the Civic Party's controversial election strategy for damaging the pan-democratic camp.

"From the start [of the campaign], the Civic Party vowed to grab two seats in the Hong Kong Island and New Territories West constituencies respectively. But that required more than 80,000 votes in Hong Kong Island and over 90,000 ballots in New Territories West, which was very difficult. This strategy harmed others and did not benefit themselves [because it won only one seat in each constituency]," he said.

In New Territories West, the Civic Party's list headed by Dr Kwok Ka-ki, with lawmaker Audrey Eu Yuet-mee ranked second, netted 14.5 per cent of the votes. Under the proportional representation system, a slate needed only 11.1 per cent of the vote, at most, to win a seat.

Had the estimated 38,000 excess votes on Kwok's list been cast for the two Democrats' lists, both incumbent Lee Wing-tat and his wife, Josephine Chan Shu-ying, might have been elected. Lee, with 6.6 per cent of the vote, lost to Leung Che-cheung of the Democratic Alliance for the Betterment and Progress of Hong Kong, by 985 votes. Leung won 6.8 per cent of the vote.

New Territories West used to be dominated by pan-democrats, with five of the eight seats. This time they secured only four of the nine seats up for grabs, even though they won 40,000 more votes than in 2008.

In Hong Kong Island, the pan-democrats' vote share edged up 1.4 percentage points to 54.8 per cent. Yet they won only three seats - down from four in 2008.

Dixon Sing Ming, associate professor of social science at the University of Science and Technology, attributed the pan-democrats' setback partly to the Democratic Party's confrontation with People Power.

In New Territories East, Democrat Emily Lau Wai-hing retained her seat but won fewer votes than People Power's Raymond Chan Chi-chuen. That constituency has an exceptionally high number of voters aged 18 to 20, who tended to support People Power more strongly than older voters.

Sung sees gloomy prospects for pan-democrats in the 2016 Legco election, because he thinks they will have difficulty overcoming their factional splits in the short run.

But Sing said he was more optimistic, because Sunday's results showed the pan-democratic camp was still supported by a majority of voters.