The Legislative Council could spend months debating this year's budget, with radical pan-democrats planning to table at least 500 amendments in a repeat of last year's filibuster attempt.
And the lawmakers - who have a series of demands, including a universal pension, a cash handout and pay cuts for "useless" officials - believe they have sound legal grounds to force a debate on each amendment and overcome any attempt to cut discussions short.
People Power's Albert Chan Wai-yip and Raymond Chan Chi-chuen yesterday submitted 261 amendments to the budget bill, which goes before Legco on April 16. League of Social Democrats chairman "Long Hair" Leung Kwok-hung and independent Wong Yuk-man each plan more than 100 amendments, some of which have already been lodged.
The deadline for amendments is midnight on Monday, and the Legco Secretariat said it had received 386 by last night.
The People Power pair said their amendments were "carefully crafted to minimise the legal grounds for the Legco president to halt the debate".
Last year's budget debate was halted by Legco president Jasper Tsang Yok-sing after 109 hours, after radicals tabled more than 700 amendments. Tsang cited section 92 of the Legco rules of procedure, authorising the president to act "as he thinks fit" in situations for which no procedure has been set.
"We have filed fewer amendments compared with last year, with all 261 items this year being concrete and meaningful," Albert Chan said. If all of the amendments are discussed, he believes the debate could run until June - the month the government's provisional funding runs out.
"We expect there would not be too many meetings inserted during the Easter holiday so the debate could easily run into June," he said.
The government is not believed to have any contingency plans in the event the budget fails to pass by the end of June.
Since last year's filibuster, Tsang has tabled two proposals to change the rules of procedure, allowing lawmakers to put forward a motion to close a debate or set a time limit on it.
But Raymond Chan said a lack of consensus on the proposals meant Tsang retained the discretion to halt or allow the debate. "If Tsang approves our amendment applications there is little ground for him to abruptly end our debate," Chan said.
As well as a universal pension and a HK$10,000 handout, the lawmakers want pay cuts for officials they say are "useless", including Executive Council members and Andrew Fung Wai-kwong, the chief executive's information co-ordinator.
The Civic Party's Claudia Mo Man-ching is the only other lawmaker to file any amendments.