The damage caused by the Gary Cheng Kai-nam scandal has not only cast immediate doubt on the DAB's ability to secure two of the five seats in the Hong Kong Island constituency. It also means the party has to find someone to replace Mr Cheng as vice-chairman, said Professor Lau Siu-kai, associate director of the Institute of Asia-Pacific Studies at Chinese University. He said Mr Cheng's decision to close his two public relations firms and step down from the DAB's vice-chairmanship appeared to be a 'halfway house'. Mr Cheng has admitted he did not disclose to the legislature his ownership of one of his public relations firms, and that he passed a confidential government document to a business contact. Professor Lau said Mr Cheng had no alternative but to immediately declare he would give up his Legco seat if elected. He said the DAB should take 'very painful but decisive action' to regain public trust, despite chairman Tsang Yok-sing's long-standing relationship with Mr Cheng. This would show that the party had the ability to cope with a crisis and respected the sentiments of the people. 'If such a course has to be taken anyway, the DAB should do it right away instead of being forced to take one more step each time because this will amount to a further erosion of the party's credibility,' he said. This was despite the fact that Mr Cheng was one of the party's few political stars, he said. Mr Cheng has been described as one of the 'four big shots' in the DAB. Professor Lau said the chances of success for Mr Cheng's running-mate, Choy So-yuk, were now marginal. It had previously been predicted she would be elected on the back of Mr Cheng's popularity. Professor Lau warned that the party on Hong Kong Island could lose a substantial number of votes very quickly. Ma Ngok, assistant professor of the Hong Kong University of Science and Technology's division of social science, said the DAB should take prompt disciplinary action against Mr Cheng to help contain the damage. Allen Lee Peng-fei, former chairman of the Liberal Party, said the best way to save the DAB and its reputation was for Mr Cheng to declare immediately he would not take up the seat if he was elected. 'There is no alternative . . . it's a breach of confidence on his part,' Mr Lee said. 'The Democratic Party would not let him off [once in the new legislature]. Whoever lets him in, will be a sinner.' He was referring to the potential censure Mr Cheng could face in the new lawmaking body. Mr Lee added: 'He [Mr Cheng] might still win because of the proportional representation system. But he has to swear allegiance to the SAR. Who will believe him?'