The Progressive Democrats party has launched its campaign for a Yes vote in next month's referendum on citizenship.
The party claims the proposed change will not diminish the rights of non-citizens living in Ireland.
The Minister for Justice is the driving force behind the proposal, and despite some initial concerns among some party members on the timing of the referendum, there was a full turn out for today's launch.
Mr McDowell denied suggestions that the proposed change would leave some children stateless.
Under international law, children born here who do not qualify for any other nationality, will become Irish citizens.
The Tánaiste, Mary Harney, has also denied that the change would adversely affect migrant workers she had given work visas to.
Children's Rights Alliance urges No vote
Earlier, the Children's Rights Alliance, which represents 78 organisations dealing with the rights and welfare of children, called for a No vote.
Speaking on RTÉ Radio, the alliance's Chief Executive, Ray Dooley, said that passage of the referendum would be a backward step for children's rights.
The Minister of State with responsibility for Children, Brian Lenihan, defended the proposed constitutional change, saying it would bring Ireland in line with other EU states.
