A new group has today launched its campaign for a No vote in the upcoming marriage referendum.
First Families First says it is concerned that the referendum as proposed would "amount to an act of vandalism against the Constitution".
The group argues that the amendment, as it is currently phrased, would undermine the biological connections between parents and their children.
Gerry Fahey is one of the three members of First Families First, alongside journalist John Waters and former MEP Kathy Sinnott.
Mr Fahey says there are differing views within the group on same sex marriage but they are against the referendum as it currently stands.
He said: "On the issue of same sex marriage, my own personal view is that I support same sex marriage.
"I'm opposed to the referndum that the Government has put forward and will be voting no on it.
"If the Government include the amendment put forward by First Families First I will then vote Yes. You have to look at all the sectional interests involved."