Labour Senator Aodhán Ó Ríordáin is mounting a legal challenge to planning permission for apartments in Howth.
He has leafleted residents and plans to hold a meeting on Monday to organise a judicial review.
Those against it say the eight-storey blocks are not in keeping with the area, while others have pointed out homes are badly needed.
Senator Ó Ríordáin says he has no problem with the Marlet Group building new homes but says local fears are being ignored.
He said: "I'm not opposing the development, what I am opposing is the scale and the over development of a site that'll lead to potential subsidence that effects lands and houses on Balscadden road and Asgard Park to the rear of the development."