Fine Gael has been granted leave by the High Court to bring a legal challenge to the Government’s delay in calling the Waterford and Dublin by-elections.
It follows victory last week in a similar case taken by Sinn Féin’s Pearse Doherty over the failure to move the writ in Donegal South West for 18 months.
The Doherty decision is awaiting appeal.
These latest challenges have been brought by Fine Gael Constituency Chairman for Dublin South Michael Van Turnhout and Dáil candidate Senator Paudie Coffey for Waterford.
The Dublin South constituency has been down a TD since the resignation of George Lee as a Fine Gael deputy in February.
The Waterford seat has remained vacant since Fianna Fáil’s Martin Cullen stepped down for health reasons in March.
In an affidavit Paudie Coffey told the court that Waferford’s under-representation is "undemocratic and contrary to the constitution" and comes at a time when "there have been a number of blows to the economy" including the loss of jobs at Waterford Crystal.
Mr Justice Michael Peart granted leave for both cases to go to a full hearing and put them back until November 22, having been pressed that these were urgent matters.