Although such a revision would throw the election plans of all political parties into disarray, several TDs told the Sunday Tribune this weekend that the constitution's strict guidelines for equality of representation across constituencies "cannot be ignored". Preliminary census figures released last week showed several constituencies to be outside those guidelines and ripe for a constitutional challenge.

In addition, the Sunday Tribune has learned that, contrary to government claims that it could not revise the constituencies until the final figures had been released, there is a precedent for change based on preliminary results. The FF government of 1947 oversaw major boundary changes, including the provision of an additional nine TDs, in 1947. It argued that although the census figures were "provisional", they were "sufficiently definite" to "enable us to proceed with the revision now".

Crucially, those constituency changes were introduced just seven weeks before the general election of February 1948. Environment minister Dick Roche referred to this precedent himself in a Dail debate of June last year.

The Sunday Tribune also understands that initial legal soundings taken by the government last week suggested the issue was not as clearcut as previously thought and that . . .contrary to the advice of the Department of Environment . . .there could, after all, be a constitutional problem.

The attitude within government has changed dramatically since last Sunday, when this newspaper predicted that the census figures would show several constituencies to be unconstitutional. The insistence of ministers that there would be no change before the election has given way to an acceptance that there is a real possibility that a radical shakeup of the constituencies could be forced upon it by the courts.

Calling for a review, Labour's Joan Burton said a consensus was now emerging in the Dail that "you can't ignore the constitution. It would be a foolish minister that would take a chance to ignore it, " she said.

A constitutional law expert this weekend told the Sunday Tribune that only the Supreme Court could decide on the matter. "It's a very serious issue and it'll have to go all the way to the Supreme Court, " said John O'Dowd of the UCD law school. Another expert, Eoin Carolan of the Trinity College law school, agreed the key issue was whether the provisional figures could be used.