The Fine Gael leader, Mr Michael Noonan, has been criticised by the Pro-Life Movement for his repeated calls for a television debate with the Taoiseach.
A spokesman said yesterday the Fine Gael challenge to Mr Ahern was "nothing more than a political ploy to win votes" and had "nothing to do with informing the public of the very serious issues involved" in the referendum - the Pro-Life Movement is calling for a Yes vote.
The spokesman called on Mr Noonan to put forward alternative proposals to those outlined in the proposed amendment.
Criticising his characterisation of the referendum proposals as "uncertain", the spokesman said the only uncertainty of which the Pro-Life Movement was aware was "Mr Noonan's persistent policy of refusing to come out with a coherent policy which would protect the unborn and support expectant mothers.
"The amendment will remove the 'uncertainty' which he refers to. It will restore and improve protection for the unborn baby in harmony with Article 40.3.3 of the Constitution.
"Most significantly, the amendment will demonstrate that the Irish people still express true care and compassion for mothers with unexpected pregnancies," he said.
The Pro-Life Movement, a separate organisation to the Pro-Life Campaign, begins its push for a Yes vote this weekend.
Volunteers will deliver 300,000 leaflets to every home in the State, with another 500,000 to be delivered and handed out on the last Sunday before the vote.
It will also run cinema advertisements and will post advertisements on bill-boards, bus-shelters, in DART and train stations and on the backs of buses. A 30-ft mobile advertising unit will travel from town to town.
Pro-amendment rallies and meetings are also planned and a lamp-post campaign is already under way.
Asked if it was worried that the tide seemed to be turning against the amendment, the Pro-Life Movement said it remained confident of a Yes result.