Hong Kong’s Democratic Party has pledged to support a primary held by the opposition camp after backing seven lawmakers to seek re-election, and help the bloc secure a majority in the Legislative Council vote in September.

The party endorsed the lists of prospective candidates in a special meeting on Sunday, setting the stage for the autumn vote, with the line-ups of most major parties in both camps revealed.

The opposition was given a boost of confidence by its landslide victory in the district council elections in November that came on the back of months of anti-government protests triggered by a now-withdrawn extradition bill.

But that popularity has sparked greater competition within the camp, with more independents or localists considering a run.

Members of the bloc reached an initial consensus to hold the primary in July and allow voters to choose which pro-democracy candidates to field for September.

Speaking to the press on Sunday, Democratic Party leader Wu Chi-wai, endorsed for a run in Kowloon East, pledged his organisation would take part and obey the results.

“This election is a battlefield to rebel against the authoritarian regime,” Wu said. “The Democratic Party will coordinate with the mechanism in the primary in hope of attaining more than 35 seats.”

The party will field one list of candidates in each of the five geographical constituencies. Apart from Wu, the party endorsed Ted Hui Chi-fung for Hong Kong Island, Helena Wong Pik-wan for Kowloon West, and Andrew Wan Siu-kin and Lam Cheuk-ting in New Territories West and East respectively.

Roy Kwong Chun-yu and James To Kun-sun, incumbent “super seat” lawmakers of the District Council (Second) functional constituency, will consider running in two separate lists.

Under the primary mechanism, coordinated by University of Hong Kong law Professor Benny Tai Yiu-ting, all prospective pro-democracy candidates are asked to participate and follow the outcome.

More than 45,000 people have signed an online petition vowing not to vote for candidates who refuse to drop out or regroup if they lose in the primary.

Compared with the Legco election in 2016, the opposition bloc is more deeply coordinating its campaign to maximise candidates’ chances as Beijing takes an increasingly prominent role in Hong Kong’s affairs.

Earlier this month, the Civic Party announced its member Andy Yu Tak-bo, vice-chairman of Yau Tsim Mong district council, had withdrawn from the upcoming race after discussions with other pan-democrats.

The pro-establishment camp is also planning its line-ups. The Democratic Alliance for the Betterment and Progress of Hong Kong, the largest in the bloc, is considering putting forward nine lists for the five geographical constituencies and one list led by party chairwoman Starry Lee Wai-king to contest the “super seat”.