Fianna Fáil grassroots members have been urged to oppose Micheál Martin's call for the liberalisation of abortion laws.
After his significant intervention in the debate, going against a policy agreed at the Ardfheis in October, Mr Martin said it was a personal decision and not a party political one.
The opposition leader called for the Eighth Amendment, which gives equal right to life to the mother and the unborn child, to be removed from the Constitution.
He also said he would support access to abortion in the first trimester.
But Bobby Aylward, TD for Carlow-Kilkenny, said the majority of ordinary rank-and-file Fianna Fáil members were anti-abortion.
He encouraged the grassroots to oppose Mr Martin's call for reform.
And he also called for other TDs and senators who hold anti-abortion views to make their opinions known.
"We need to let our voice be known and that Fianna Fáil is not gone all liberal all of a sudden and on some kind of a social agenda, that we're still there to represent the people that elected us," Mr Aylward said.
"I'm going to call on like-minded members next week and I'm going to see if I could get more of them to make their position known on pro-life.
"I was taken aback and surprised but having said that it is his (Micheál Martin's) personal opinion and he's entitled to that.
"We all agreed that, it's an open vote, a free vote."
Mr Aylward said he wanted the grassroots of the party to know he was prepared to fight for retention of the Eighth Amendment of the Constitution as agreed at the Ardfheis.
Mr Martin made his position known on the second day of the Dail debate on the future of the constitutional restrictions on abortion.
In a departure from previous positions on the issue, the Fianna Fáil leader said he changed his mind after hearing the evidence in a specially-convened Oireachtas committee.
That committee has recommended repeal of the Eighth Amendment. It also backs unrestricted access to abortion in the first 12 weeks.
A referendum on the issue is expected in late May or early June.
Mr Martin told the Dáil he was keen to see legal advice being drafted for the Government on whether the Eighth Amendment should be repealed or repealed and replaced.
He also said provisions should be made for cases of fatal foetal abnormality and serious threats to the health of the mother.