Lawmaker Cheng Chung-tai admitted on Sunday that he had described the public as "morons" for thinking Civic Passion, which he heads, is a localist group.
His admission comes after a leaked recording from a Civic Passion meeting was posted on the internet.
The New Territories West councillor also said he had been forced to "pretend to be friends" with Youngspiration’s Sixtus Leung and Yau Wai-ching, who were also voted in as lawmakers last year but were later barred from taking up their seats by the courts.
Cheng wrote on social media that it was regrettable that some members of his group had leaked the audio recording.
Civic Passion was originally a radical activist group and had links to former lawmaker Wong Yuk-man. But at the beginning of the year, Cheng said the group was dropping its social activism and would become a “moderate” political party.