The Democratic Party has suspended Lau Chin-shek over his dual membership.
He will not be reinstated until he leaves The Frontier, a disciplinary committee said.
Mr Lau, who did not attend the disciplinary hearing on Tuesday, said he felt 'helpless' but would respect the committee's decision.
He said he would not file an appeal nor would he quit The Frontier.
Mr Lau said: 'The democratic camp is facing its toughest period as Tung Chee-hwa has been stifling democracy since he took office. He disbanded the municipal councils, resumed the appointments system and is now damaging the rule of law on the right of abode issue.
'It's time the democratic camp knitted together instead of dragging on with trivial matters.' Suspension of membership is the second-most serious penalty, behind expulsion.