Any person who can secure 37,790 votes from members of the public – 1 per cent of the city’s registered voters – from February 7 to 22 will be regarded as a “civil candidate”.

Avery Ng Man-yuen, chairman of the League of Social Democrats, said his colleague Leung would officially declare his bid to stand as a candidate on Wednesday and launch his campaign to garner 37,790 public votes in a bid to exert pressure on his allies to formally nominate him.

The pan-democrats have been caught in a dilemma on how to make use of the 326 votes they have in the Election Committee. Some want to choose Tsang, while others called for blank protest votes to be cast.

“We want to remind pan-democrats that they are not betting on horse races now. They should not forget what they stand for when they cast their votes,” said Ng, saying Tsang had pledged to restart the political reform process based on Beijing’s restrictive 2014 blueprint.

Watch: Carrie Lam kicks off election campaign

Meanwhile, Tsang faced a rare protest on Tuesday when his talk at Shue Yan University was briefly disrupted by a group of student activists who condemned him for supporting a national security law and accepting the 2014 ruling on political reform.

His key rival, Lam, also faced a setback when her newly launched Facebook page attracted more than 33,000 angry emoticons over a video showing youngsters teaching her how to use social media. That stood in sharp contrast to Tsang’s page, for which a recent post drew almost 8,900 likes and just 22 angry reactions.

Lam attributed her low popularity to the hot potatoes she handled in past years and her close relationship with incumbent leader Leung Chun-ying.

“If the chief executive is not popular, then naturally whoever is very close to him shares part of that blame or that pain,” she told TVB in an interview.

Separately, Professor Joseph Sung Jao-yiu, the vice-chancellor of Chinese University, told reporters that he had been approached by a candidate who asked him to join that person’s election team, but he declined the offer.

Gabriel Leung, dean of the University of Hong Kong’s medical school, also said he had rejected “more than one offer” from chief executive contenders to join their campaign.

Additional reporting by Peace Chiu and Emily Tsang