Fianna Fáil has failed in an attempt to invite the Attorney General into the Seanad to speak on the Fennelly report.
The party had invoked Standing Order 56 of the Seanad rules which says that an Attorney General may be heard in the upper house.
However, in a vote on whether such an invitation should be extended, the Government won by 27 to 20.
Earlier, the vote count was 26-19 but when it was formally announced it was amended because a Senator pressed a button twice and so it was changed to 26-18.
However, a second walk-through vote took place and the numbers changed again to 27-20.
Fianna Fáil leader in the Seanad, Darragh O'Brien, says Máire Whelan needs to be heard.
He said: "She herself will have a unique and important perspective on what really happened around that time.
"I do believe that it would be important that she answer questions around some of the contradictory evidence that was given and the fact that her evidence had to be changed four times during the course of that commission."