About 10 Fine Gael TDs and senators will vote against the new abortion legislation, a member of the party has claimed.
Brian Walsh, TD for Galway West, said he believes the opposition in the party to the contentious reforms is bigger than had been anticipated.
"There won't be a lot more than 10 voting against, there won't be a lot less than 10," he said.
Fine Gael TD Peter Matthews and Senator Fidelma Healy Eames have said they will not support the legislation as it stands.
The inclusion of a clause to allow a pregnant and suicidal woman the right to an abortion has sparked massive division among politicians and medics, in particular psychiatrists.
The legislation is expected to be passed by the time the Dail breaks for the summer.
Mr Walsh refused to put a number on Fine Gael TDs and senators who will vote against it but he warned about the large contingent of young and first-time Dail TDs in the party.
"They are wrestling with their conscience," he told RTE. "They are choosing between their conscience and their livelihoods."
Mr Walsh suggested that Taoiseach Enda Kenny might have to reconsider threats that Fine Gael TDs and senators who vote against the legislation will be excluded from the parliamentary party.