Fianna Fáil Senator Don Lydon has told the Flood Tribunal he will quit his council seat and his job as a psychologist in St John of God's hospital.
Senator Lydon said he will concentrate on his Seanad post, and will give up his other two jobs from July next.
Earlier, he said he was stupid to try to grab a cheque from a Green Party councillor at a council meeting.
Senator Lydon was being questioned about a Dublin County Council meeting ten years ago during which Green Party TD, Trevor Sargent, produced a cheque from a developer.
He denied that he had grabbed Deputy Sargent around the neck, but said he had grabbed him from behind to try to see who the cheque was from.
Senator Lydon said he was annoyed that Mr Sargent would not show them the cheque and did it out of 'devilment'.
Earlier Senator Don Lydon answered questions about his inaccurate statement to the Fianna Fáil inquiry on political donations.
Senator Lydon said he had forgotten about a £5,000 donation from a man who had an interest in getting land rezoned in 1992 when he gave his statement to the inquiry eight years later.
He told the inquiry he just floated through life and did not remember these things. He said he could not tell the inquiry what he did not know at the time.
Senator Lydon also confirmed when he discovered the payment some months after the inquiry's findings were published, he did not correct the record.
He said there was no point because the whole thing was over.
Other councillors had also subsequently discovered more donations, he said.
Senator Lydon also confirmed that Frank Dunlop had given him the names of overseas directors of Paisley Park before he signed a rezoning motion for the land in Carrickmines.
He said he had never checked out the ownership for himself and just took what Mr Dunlop had told him.