"Some of the signatories are hoping to be middlemen … to call on different parties to make a concession. But what kind of concession could we make in fighting for genuine universal suffrage?" asked Lau after eight hours of talks involving almost 30 members. "We do not want to send the … wrong message by signing the petition."

However, Lau said she would be more than happy to sign if the petition called for a model for the 2017 chief executive election that did not allow the "screening" of candidates on political grounds.

Former party chairman Dr Yeung Sum and ex-lawmaker Cheung Man-kwong were among those invited to sign the petition, but held off doing so until the party made its decision. However, Stanley Ng Wing-fai, a member of the party's executive, stirred controversy when he signed the petition last week.

Although no one had suggested disciplinary action be taken against Ng, Lau said she believed core members should handle such situations more carefully in future to avoid misunderstandings.

The Democrats have faced accusations of being too willing to compromise to secure reform, not least in 2010, when the party's lawmakers voted in favour of a reform package many pan-democrats felt did not go far enough.

Lau stressed that the party would not "pocket" any plan that would see the city's leader elected by one person, one vote from a narrow choice of candidates.

The campaign comes amid pressure from the local and central governments for pan-democrats to accept a reform package for 2017 that falls short of their expectations as a first step towards change. National People's Congress chairman Zhang Dejiang said last month that 2017 would not be the "be-all and end-all", while the local government last week launched a campaign calling on Hongkongers to set aside their differences on reform.

Any reform package will need a two-thirds majority in the Legislative Council, meaning the government must win over about five pan-democrats.

"There has been a suggestion that the Democratic Party would pocket [an unsatisfactory proposal] … and its six votes in legislature would all support the government's proposal," Lau said. "But that will never happen."

She added: "North Korea also has one man, one vote, but there's only one candidate."

Lau said the party would work with Occupy Central, the group planning to block streets in the business district if no acceptable reform plan is forthcoming.

Former chairman Albert Ho Chun-yan added: "Pocketing fake universal suffrage might be even worse than making no progress [on reform]."

But Lau stressed that the party wanted to put its views to Beijing officials before the Standing Committee of the National People's Congress set a framework for reform later this month. It wanted talks as soon as possible, but, Lau said: "So far we have not heard anything from them."

Meanwhile, Lau said there was little support for party member Tik Chi-yuen's view that seeking talks but supporting protest left the party's stance ambiguous.