Frederick Fung, a veteran pro-democracy legislator announced his candidacy after long speculations that he would run, and cited that he was unhappy the camp had decided on another veteran, Lee Cheuk-yan, as Lau’s backup, in case of disqualification of the candidacy of Lau Siu-lai, one of the six ousted pro-democracy legislator in the 2016 oath-taking controversy who was commonly backed by the pro-democracy camp. Fung previously lost in the pro-democracy primary in the March by-election to Yiu Chung-yim and subsequently quit the Association for Democracy and People's Livelihood (ADPL), in what was seen as a move for him to run as an independent in the by-election. Fung said he ran because he opposed the pro-democrats for monopolising the candidacy selection process. Political observer Dr Chung Kim-wah said Fung’s decision had caused uncertainty for the pro-democrat campaign would easily attract thousands of votes from the pro-democracy voter base that would cost pro-democrats the election.