Organisers say Occupy Central's unofficial referendum united nearly 800,000 people in a demand for universal suffrage.
But it didn't unite the pan-democratic camp on what its next steps should be.
A day after the three-track proposal of the Alliance for True Democracy won the 10-day poll, the Democratic Party confirmed it would quit the alliance.
Student group Scholarism, meanwhile, stopped short of pledging full support for the alliance plan and called for an end to "mud-wrestling" among parties.
Scholarism and radical group People Power urged the Democratic Party's six lawmakers to stick with the alliance.
But Democratic Party chairwoman Emily Lau Wai-hing said: "We considered the whole thing carefully before we decided to quit. Whether the alliance's proposal could win … is not part of our consideration."
Their departure leaves the alliance with 20 lawmakers.
Lau said the party would continue to push for the three-track proposal with other pan-democratic allies with whom they had mutual trust and respect.
The party decided in May that it wouldn't attend alliance meetings after the Occupy Central-organised "referendum" because of a row with People Power and fellow radicals in the League of Social Democrats.
The alliance's proposal won with nearly 334,000 votes, or 42.1 per cent of the 792,808 valid ballots cast.
It calls for the public, political parties and a nominating committee to put forward candidates. Scholarism's second-placed proposal would allow the public and a nominating committee formed by 35 directly elected lawmakers to put forward candidates.
Convenor Joshua Wong Chi-fung said yesterday that while he respected the poll results, he would continue to advocate public nomination in other ways.
Asked if Scholarism would support the alliance's scheme, Wong said: " I'll have to see what happens in the meeting with the alliance next week. The precondition for our support is that they must stop mud-wrestling."
He said he wanted to ask pan-democrats whether they agreed public nomination was a must and whether they would seek a nominating committee formed as democratically as possible.
He appeared to be referring to the Democratic Party, which has said public nomination could be done away with if the government promised a reform plan that complied with international standards of universal suffrage.
Alliance convenor Professor Cheng Yu-shek said he hoped the Democrats would stay.
"After all, it is the biggest party in Hong Kong, with the longest history," he said.
Former chief secretary Anson Chan Fang On-sang said she felt encouraged by the poll result, and would continue to push her reform proposal, which does not include public nomination.
Information technology representative Charles Mok, seen as a moderate democrat, also urged the groups not to fight.
"If we stay united, the government will have to think about ways to respond to the [referendum] and there's a chance that it will soften its stance," Mok said.