Albert Ho Chun-yan has accused his fellow chief executive contender Leung Chun-ying of having a high-handed leadership style and foresees strained ties with pan-democrats if he is elected.
Ahead of Sunday's vote in which the 1,193-strong Election Committee will pick Hong Kong's leader for the next five years, the Democratic Party chairman cast doubts on the integrity of Leung, now widely seen as likely to win, and said he would have difficulties working with him.
'The problem with [Leung's] integrity is bigger than his competence ... I think he can be ruthless and may try to achieve his aims by all means. Needless to say, many people believe that he is an underground [Communist Party] member,' he told the South China Morning Post.
'He can be unscrupulous and reckless and may be bold enough to do many things.' Ho said this was something Hongkongers did not want to see.
He said a rift had developed between Chief Executive Donald Tsang Yam-kuen and the opposition and pan-democrats, but this would escalate and become more serious under Leung. Tsang steps down in June.
Ho suggested that Leung's followers might have been behind the attacks on Henry Tang Ying-yen, his main rival for the top job, with supporters like Lew Mon-hung keen to launch negative campaigning.
Lew earlier admitted he had made contact with controversial businessman Kwok Wing-hung, nicknamed 'Shanghai Boy', because Kwok claimed he had negative material about Tang.