Hong Kong goes to the polls tomorrow, and some of the city's most senior and best-known politicians could be forgiven a sleepless night as their fate lies in the hands of 3.4 million voters.
Polling has shown support ebbing away from the established pan-democratic parties, the Civic Party and the Democratic Party. Ratings for candidates of the Democratic Alliance for the Betterment and Progress of Hong Kong, the Beijing-loyalists, have also been sliding.
The radical People Power, though, has seen its support rise, while more respondents are saying they don't plan to vote.
The key question of the election - whether the pan-democrats can retain one-third of the 70 seats in the Legislative Council, allowing them an effective veto over constitutional change - remains firmly in the balance, with observers describing their 24-seat target as a huge challenge.
With few candidates polling at much more than 10 per cent and margins of error between two and four per cent, tracking polls by the University of Hong Kong's public opinion programme must be taken with a pinch of salt.
But following such movements can, says Dr Li Pang-kwong, a political scientist at Lingnan University who has been doing polls for more than a decade, be a useful guide to the way the vote is likely to go.
"I think [the figures] have considerable value for reference … if candidates' support ratings change within a month with an obvious trend [exceeding the margin of error]."
Thirty-five lawmakers will be elected in five geographical constituencies, another 30 in functional constituencies - representing sectors such as labour, medicine, education and various industries. Five will be chosen to fill the new so-called super seats, chosen by a citywide ballot of 3.2 million voters who are not among the minority with votes in a functional constituency.
The picture is complicated because Hong Kong elects its lawmakers using a system known as the "closed list". Political parties put forward a slate of candidates in the hope of getting their first choice elected by meeting a quota, calculated by dividing the number of votes cast by the number of seats available. They then hope they will have enough extra votes for their second-ranked candidate to be elected.
But that's difficult as most of the winning candidates never reach the quota, so seats are filled by what is called the "largest remainder" method. If no more slates reach quota, candidates with the next-highest number of votes are elected. Assuming a quota of 40,000, a slate with 70,000 votes might have a chance of getting the second candidate on its slate elected. But splitting the vote between two slates, with 35,000 each, is much more effective. The Democrats had success with such a strategy last time and are doing so again, while the DAB is attempting a similar tactic.
With few slates likely to get enough votes to have a second candidate elected, voters face a temptation to move their vote from a "safe" candidate to one from the same camp who might lose. But, of course, if enough voters do that, the "safe" contenders can find themselves fighting for their political lives.
The party hardest hit by the polling downturn is the Civic Party, with four of its five slates losing popularity. Its incumbent in the fiercely contested New Territories East seat, Ronny Tong Ka-wah, topped the poll with nine per cent of the votes when polling started, but is now at just four per cent. While that still puts him sixth, with nine candidates to be elected, a fall in his support that is well within the margin of error could see him ousted.
Tong believes voters are convinced he has enough support to win and are switching their backing to other pan-democratic teams. He was forced to step up his campaign and in a tearful speech on Wednesday urged voters not to believe rumours that he would win anyway.
Kevin Mak is the kind of voter who will be preying on the mind of Tong and company tonight. Four years ago he voted for Civic Party leader Alan Leong Kah-kit in his Kowloon East constituency. This time, sure that Leong will win, he's considering backing a hopeful from a radical group.
"Leong is a political star, he should be safe, so I am considering voting for People Power's Wong Yeung-tat this time," Mak says. "Wong might not have the track record of serving Kowloon East residents, but he is a new and relatively disadvantaged voice, and I agree with his ideas."
Leong has also stepped up his campaign after seeing his rating fall from 17 per cent to 13 per cent and an internal poll putting him at 14 per cent, ranking him third in a constituency that elects five lawmakers. Wong has seen his support increase to eight per cent, giving him in a chance of the fifth and final seat.
The trend is visible elsewhere, according to the party's campaign chief, Bill Lay Yan-piau.
"[Given] our initial high ratings … for example, in Kowloon West, when the ADPL [Tam Kwok-kiu from the Association for Democracy and People's Livelihood] was calling voters, asking them to change their minds, some might decide to 'help' the ADPL instead."
The competition between the pan-democrats - and, in particular, constant attacks by People Power on its more moderate erstwhile allies - could jeopardise the camp's chances as well, says Ivan Choy Chi-keung, a political scientist at Chinese University
"The [pan-democrats'] campaign is especially tough this year with People Power's attack, which has been more malicious than the pro-establishment camp. Pan-democratic support might not only flow within the camp, but may be [lost] to independent candidates."
In a worst-case scenario for the pan-democrats, Choy says the parties could win 21 seats - fewer than the 23 they won in 2008, when there were just 60 lawmakers before the "super seats" and the expansion of geographical constituencies.
The row between pan-democrats is also having an impact on the perceptions of voters.
Rainbow Leung, a marketing executive living in Stanley who has never voted before, may cast her ballot for a pro-establishment candidate because she is disappointed with the infighting among pan-democrats.
"When I was watching the televised forum, I felt: if they are determined about improving people's living and democracy, why can't they put aside their [differences in] political stance?" Leung says. "I want the economy to develop and the wealth gap narrowed, but some parties were only accusing each other, and criticising the government for being corrupt. I want to know what their actual plans and solutions are."
There are issues too for the pro-establishment camp, where the Federation of Trade Unions is putting up slates in competition with its allies the DAB. There was a rare sign of discord on Thursday, when FTU heavyweight Cheng Yiu-tong criticised the DAB for telling voters not to vote for the unionists as they already had enough support to win - conduct he called "ungentlemanly".
Unionist "super seat" contender Chan Yuen-han has seen her poll rating fall by five percentage points to 13 per cent, although she is still the best-ranked candidate in the race. And she's not the only one. In Kowloon East, the DAB's Chan Kam-lam has seen his rating fall from 17 per cent to nine per cent, while DAB chairman Tam Yiu-chung's backing in New Territories West is down by more than half, from 15 per cent to seven per cent.
But Li, of Lingnan University, says that might be a sign of their confidence. "They estimated that they have more than enough votes, so they have to make way for their pro-establishment allies who have not secured a seat yet."
But there is one factor that makes these elections tough to predict - a huge proportion of voters who say they are undecided, will not vote or won't reveal their choice to pollsters.
On Hong Kong Island, for example, 12 per cent of voters said this week that they would not be voting or refused to state their choice - compared to almost zero a few weeks back. Some 25 per cent remain undecided. In Kowloon East, the proportion of non-voters is up to 17 per cent, from 3 per cent.
Dr Law Chi-kwong, the Democratic Party member in charge of analysing the popularity of candidates, believes it shows voters are disillusioned about the election.
"The chaos this year has been shocking … disunity among pan-democrats is annoying our supporters. So in the past, we heard voters encouraging us to be united, but this year, few people were saying this. Instead they were asking: 'what are you guys doing?' I think the 'Cultural Revolution-style' attack and internal strife is doing no good for [pan-democratic candidates]."