Fine Gael plans to launch its campaign for a Yes vote in the Children's Rights Referendum next Monday.
The party's director of elections Leo Varadkar said the initial budget would be €150,000, saying that it wanted to avoid what he called an "overly flashy" campaign.
He said he was conscious of the Government's defeat in the Oireachtas inquiry referendum and consequently Fine Gael would not be taking anything for granted.
The Children's Referendum will be held on Saturday 10 November.
Mr Varadkar said the party would also be prepared for the emergence of a no lobby as the campaign progressed.
Former MEP Kathy Sinnott has previously said the issue at stake in the referendum is how best to protect children.
Ms Sinnott said the "devil was in the detail" of the wording and that the more she spoke to legal experts, the more doubts she had.