Three of the four Mayo senators voted in favour of a referendum on abortion in the Seanad last night.
The bill to allow a referendum on the Eighth Amendment be held passed second stage in the Seanad late last night, by 35 votes to 10.
It is now likely the bill will pass all stages today.
Mayo Fine Gael senators Michelle Mulherin and Paddy Burke voted in favour of holding a referendum on the 8th amendment, as did Sinn Fein Senator Rose Conway-Walsh.
Erris-based Fianna Fail Senator Keith Swanick did not vote last night as he was absent for medical reasons.
Ballaghadereen-based Senator John O’Mahony was the only Fine Gael Senator to vote against the Bill to hold a referendum.
Roscommon FF Senator Terry Leydon also voted against, while Fine Gael Senators Frank Feighan and Maura Hopkins voted in favour of holding a referendum.
The matter is not yet concluded, and moves to Committee and Report Stages in the Seanad today.
The Seanad is expected to approve the Referendum Bill this evening allowing the vote on abortion to take place.
The 25th of May had been suggested as the probable date for the public to go to the polls.
But Tanáiste Simon Coveney has suggested it could happen a week earlier than expected: