Two Basic Law Committee members are at odds over whether public nomination should play any role in the chief executive election in 2017.
Albert Chen Hung-yee, a Hong Kong University law professor, reiterated for a second time that the public should be allowed to recommend candidates for the nominating committee to consider. But fellow committee member Maria Tam Wai-chu dismissed the idea as "impractical".
The disagreement between the two Beijing advisers has highlighted the difficulty of reaching consensus on political reform.
Chen and Tam were speaking after a forum on the RTHK television show Legco Review, which will be screened next Thursday.
The debate marks the first time this year that Chen and Tam have sat down with pan-democrats in a televised event to discuss universal suffrage.
Chen's stance has been regarded by observers as an effort to seek middle ground, after Beijing's liaison office director, Zhang Xiaoming , shot down the pan-democrats' idea of public nomination last week.
Pan-democrats want people who win sufficient nominations from the public automatically to become candidates. Critics say that idea contravenes the Basic Law, which requires candidates to be put forward by a nominating committee.
Chen said that although public nomination for chief executive candidates had uncertain legal underpinnings, the concept was already established in the city's political and legal system.
"The existing Legislative Council ordinance provides for joint nomination by 100 or 200 citizens for candidates who want to participate in direct elections in geographical constituencies," he said, adding that any public participation in the nomination of chief executive candidates should be mediated through a nominating committee, as laid out in the Basic Law.
"The rationale behind [public nomination] deserves to be the government's reference point."
Speaking separately, Tam said Chen's idea was unlikely to win support, citing "practical" concerns.
"If you include public nomination, how can you say you cannot include political parties' nominations … the business sector's nominations. This kind of debate will be never-ending," Tam said, adding there might be difficulties in asking for the identity card numbers of people prepared to sign nominations.
Meanwhile, the propaganda chief of the central government's liaison office in Hong Kong yesterday warned that the Occupy Central movement for full democracy would push the city towards turmoil.
In an article in Ming Pao Daily, Hao Tiechuan said the civil disobedience movement had "subverted Hong Kong's traditions" and "gone against Hongkongers' values and lifestyle" and would harm "innocent citizens
- the businessmen, tourists and workers in Central". The liaison office's director general of publicity, cultural and sports affairs added: "Isn't the movement trying to push Hong Kong towards turmoil?"
Wu Wai-chung, chairman of the Neighbourhood and Worker's Service Centre, said the non-violent movement was the pan-democrats' last resort.
"Saying the action will push the city towards turmoil is defamation," he said.