Senior and backbench government politicians are privately conceding it is "very unlikely" that a referendum can be held in that timescale, despite the confidence of minister for children Brian Lenihan that it can be done.

They are concerned about the complexities involved and the possibility that a constitutional change could create unanticipated legal loopholes, as has happened in the past.

It is thought that copperfastening the rights of children could have implications for the government's deportation programme. Legal sources are questioning whether children born in Ireland and whose rights were specifically enshrined in the constitution could be deported . . . regardless of the citizenship referendum . . . and whether also their parents could be deported in those circumstances.

Last week's Supreme Court ruling on the baby Ann case and the High Court decision on frozen embryos has focused politicians' minds on the difficult issues involved in dealing with children's rights and added to pessimism that they can be addressed in the short time before a likely referendum date in March or April.

"It's now fairly obvious that this isn't as simple as it looks, " one senior government politician said. "It raises all sorts of issues. If you give rights to children, are you taking them from non-children? Are you taking them from the family?

Could you have children taking their parents to court?"

Another government TD said a referendum had the potential to become "extremely divisive", adding: "In truth, I don't think it'll happen".

Even those in government who insist that the referendum will go ahead accept that the issues involved are "very complicated".

Minister Lenihan has already written to the main opposition parties and the Children's Rights Alliance inviting them to take part in a consultation process and the hope is this will be completed by Christmas.

However, Labour leader Pat Rabbitte warned that the referendum proposal was "fraught" with difficulty and said the government must present "some form of indicative wording" before any debate. "I think the proposition is ill-thought out and seems to be motivated as much by a wish on the part of the Taoiseach to have a dry run before the election. I say that because we have no clarity, no precision and no indicative wording."

Minister Lenihan said he envisaged a "bundle of amendments" being put to the people and all the articles of the constitution would be looked at, as it would be very difficult to find "a few magic words" that would address the issue.

Lenihan declined to be drawn on the likelihood of a separate amendment to the constitution to deal with the fallout from the statutory rape controversy.

However, it is understood that the government is determined to deal with this issue in a referendum.