Fine Gael has called for Cllr Therese Ridge to resign after a report into political corruption found she had accepted inappropriate donations.
However, the party exonerated TD Olivia Mitchell, who was also mentioned in the Mahon Report, claiming she had not in fact brought the party into disrepute.
A disciplinary committee found Ms Ridge had behaved injudiciously and unwisely in accepting a payment from lobbyist and former government press secretary Frank Dunlop in relation to land rezoning issues in Co Dublin.
The group also ruled that her relationship with Mr Dunlop "severely compromised" her role as a public representative and that she should have declared an interest or abstained from votes as far as he was concerned.
She must give up her position within the next seven days or face permanent expulsion from the party.
Meanwhile, a spokesman for the disciplinary committee said South Dublin TD Ms Mitchell remains in the highest good standing in Fine Gael and that no action was merited after the report claimed she accepted an unsolicited election contribution from Mr Dunlop in the 1990s.
In a statement, Ms Mitchell said she was not surprised by Fine Gael's decision to take no action against her. "The opinion of the tribunal that acceptance of such a donation was inappropriate is entirely unremarkable given that the opinion was formed with the benefit of hindsight and in the light of information about Mr Dunlop and his activities which was unknown both to me and the general public at that time," Ms Mitchell added.
She said she supported all recommendations made in the tribunal and looked forward to their implementation.
Former taoiseach Bertie Ahern, who was named and shamed in the same tribunal along with a number of his Fianna Fail colleagues, was forced to resign from the party after it emerged he had lied about receiving money in connection with planning matters.
He left the party after current leader Micheal Martin made it clear following the report's release in March that he would be expelled.