Acting Chief Executive Donald Tsang Yam-kuen could afford to see his popularity drop to 55 per cent in the next two years before facing the sack from Beijing, pollster Robert Chung Ting-yiu said. Dr Chung, head of the University of Hong Kong's Public Opinion Programme, has spent the past decade monitoring popularity ratings of top officials. He said there was room for Mr Tsang to raise his popularity if he emerged as the next leader. 'If we look at Tung Chee-hwa, his popularity was so low that even the central government panicked and felt there would be a problem if he continued to stay,' Dr Chung said. 'The point where he announced his resignation was when his ratings dropped to around 45 per cent. I would say Donald Tsang would be in a danger zone if his own rating dropped to about 50 per cent.' He said that as Mr Tung's replacement, Mr Tsang - who has yet to declare his candidacy - should keep in mind that one reason Beijing picked him was his wide acceptance among the public. He said Beijing might be less tolerant if he fell foul of the Hong Kong people. 'He should be vigilant when he sees his popularity dropping to something like 55 per cent, because the central government is not likely to tolerate anything lower than that,' Dr Chung said. He said that after the likely case of Mr Tsang's election as the next chief executive on July 10, the new leader could expect to enjoy a spell of even higher popularity due to his skillfulness in playing politics and his down-to-earth image with the public. 'There is room for him to become more popular, as we can well see that both [former chief secretary] Anson Chan [Fang On-sang] and [former premier] Zhu Rongji made it to more than 80 per cent,' Dr Chung said. 'His popularity would not likely drop to rock bottom especially since his term will last just two years.' But he sounded a note of caution about the mock polls being conducted on Mr Tsang and other challengers, saying that some figures could be misleading.