The Frontier's membership yesterday voted at a special meeting to merge with the Democratic Party.
But the group will still exist, albeit smaller in size, as a motion to dissolve it was vetoed at the meeting.
Of the more than 50 members present, 34 voted for the merger, aimed at boosting the morale and influence of the city's pan-democratic camp.
Fifteen people voted against, one abstained and one cast an invalid vote. The group has about 115 members.
Convenor Emily Lau Wai-hing, along with eight other executive committee members, will quit The Frontier and apply for Democratic Party membership tomorrow.
Two other executive committee members had not yet indicated their intentions, Ms Lau said.
A proposal to wind up the 12-year-old organisation, which required the support of 80 per cent of members to pass, was rejected with 41 votes for, 12 against and one invalid vote.