Enda Kenny yesterday announced that the referendum will be held in October and claimed that scrapping the Seanad would lead to a more effective political system.
But those opposing its abolition have pointed to comments made by the Taoiseach in 2009 – when he spoke about the "real potential" of the Seanad.
"There is a need to challenge the Seanad in the work that it does. Many people feel it's just been a cosy house for far too long. It's got real potential but it's got to be challenged in that sense," Mr Kenny said at the time.
However, in 2010, Mr Kenny pledged to hold a referendum on the Seanad in 2012.
Agriculture Minister Simon Coveney was forced to defend his boss this morning and claimed that the Taoiseach's views have "evolved" since 2009.
"At the time of that interview, Fine Gael were in the middle of looking at how we would fundamentally reform politics because that was clearly needed," Mr Coveney said.
"I think he weighed up both options. He fundamentally made the judgment as to whether we need a second house in our parliament, a second chamber in our parliament. And he came to the conclusion, like I have, that we didn't need a second one.
"And then he went to the country on that basis in the last general election and got a very strong endorsement of that policy which was part of the public debate during the general election and now he is coming true on his promise to offer the decision to the people."
Mr Coveney also pointed to the sudden change of heart by former Tanaiste and Michael McDowell – who once said he wanted to "terminate" the Seanad.
The ex-PD leader has now emerged as one the main opponents to the Government's campaign to scrap the Upper House. He claims that by scrapping the seanad, a political elite will emerge in the Dail.
Meanwhile, Social Protection Minister Joan Burton today said that individual TDs are entitled to vote whatever where they want in the privacy of the ballout box.
She was responding to comments made by the Labour chief whip, Emmet Stagg, who has vowed to oppose the abolition.