At least two Fine Gael Senators are likely to lose the party whip with a vote on the abortion legislation later today.
The first vote on the legislation in the Seanad is due this evening, and two Senators are expected to vote against the government
Paul Bradford and Fidelma Healy Eames have been vocal in their opposition to the legislation.
It will bring to seven the number of defections from the party over the Protection of Life During Pregnancy Bill.
Others are uncertain, with Michael Mullins another possibility to revolt this evening.