"The proposed package has not come easily. So tonight, I personally appeal to you all: do not let the hard work and efforts of the past two years be wasted," Tsang said in a five-minute speech Wednesday.

"I really cannot see any other option that can better suit Hong Kong's current circumstances, and be acceptable to all interested parties."

All 25 pro-democracy legislators have threatened to scuttle the package when it comes up for a vote on December 21. In order to be enacted it requires a two-thirds vote in Legco and democrats hold the deciding votes. A defeat would be a blow for Tsang's prestige.

In Tsang's address, the medium seemed very much the message, a sober plea for the community to back away from protest and support reform or face a standstill in democratic development.

A senior Tsang aide said that if the broadcast turned out to be popular with the public, it might turn out to be a regular part of Tsang's political repertory.

"We borrowed the idea from the president of the United States who appealed to the country on TV when he announced the US military invasion of Iraq," the aide said. "Tsang was advised to use his personal charisma and popularity to call for public support."

A source said the message was taped a few days ago for airing in advance of tomorrow's meeting in Shenzhen between legislators and mainland officials.

"We are now facing a real danger of our democratic development coming to a halt" if the reforms are voted down, Tsang warned.

"I have thought long and hard about whether we could develop a better and more feasible package," Tsang said, looking directly into the camera.

But the reforms have "given due regard to the aspirations of different sectors of the community."

Most pro-democrat legislators remain unimpressed, accusing Tsang of insincerity and trying to threaten the public not to join Sunday's protest.

Catholic Bishop Joseph Zen said Tsang's speech and the Shenzhen meeting tomorrow will only increase public enthusiasm to take part in the pro- democracy rally. "I think the moves [the government] is taking just days before the rally will just create a tense atmosphere," Zen said.

Tsang called on all 60 legislators to "cast their votes sensibly," as Hong Kong could only move forward to achieving universal suffrage if the Legislative Council passes the package. "Let's not miss this opportunity before us. If we choose to mark time rather than stride ahead we will be further away from our goal of universal suffrage, not closer to it," he said.

Barrister-legislator Alan Leong, of the Article 45 Concern Group, dismissed Tsang remarks. "The chief executive just meant that if you all do not pass the proposal, he will not move in the direction of universal suffrage. He is just threatening the public and failed to show any sincerity to endorse universal suffrage in future."

Slamming the government for shifting the blame for risking rejection of the proposal to legislators and the public, Democratic Party chairman Lee Wing-tat said his party will not change its stance to vote down the proposal.

Chinese University political analyst Chan Kin-man said comments made in Shenzhen by National People's Congress Standing Committee deputy secretary general Qiao Xiaoyang will have an important effect on the rally turnout, because Qiao is likely to relay the central government's views over the introduction of universal suffrage.

Nineteen pro-democracy legislators have been invited to join 43 chairmen and vice chairmen of committees and affairs panels at the forum.

Frontier convenor Emily Lau and former radio host Albert Cheng are the most hardline pro-democrats to confirm their attendance, while moderates include Association for Democracy and People's Livelihood chairman Frederick Fung, accounting sector legislator Mandy Tam and health services legislator Joseph Lee.

Former Democratic Party chairman Yeung Sum and party legislator Fred Li will attend after receiving approval from the party's central committee.

"We are all willing to do everything we can to push for the democratic process in Hong Kong," Lau said.

"We have no idea what Qiao is going to say. We hope he is willing to immediately introduce universal suffrage in 2007-08 or at least offer us a timetable.

"Let's see what he will say. But if he fails to impress the Hong Kong public, he may just push 200,000 or 300,000 more people to take part in the Sunday rally."