Prospective MEPs outside Dublin will have to campaign in as many as 15 counties during next year’s European election.

It follows a radical recasting of existing constituency boundaries which will see the advent of two new mega-constituencies in the Republic.

The number of Irish seats will drop to 11 from 12 as the European Parliament makes room for MEPs from Croatia, the EU's newest member state.

The capital retains three European Parliament seats and there will be four each in two vast new constituencies, which will be be known as Midlands-North-West and South.

Midlands-North-West comprises Cavan, Donegal, Galway, Kildare, Laois, Leitrim, Longford, Louth, Mayo, Meath, Monaghan, Offaly, Roscommon, Sligo and Westmeath. The constituency will run from the Atlantic coast in the northwest to the Irish Sea in the east.

South is similarly large, comprising Carlow, Clare, Cork, Kerry, Kilkenny, Limerick, Tipperary, Waterford, Wexford and Wicklow. Up to now there were three seats each in four constituencies: Dublin; East; South; and North-West.

Fine Gael MEP Jim Higgins, now of North-West, will have to expand his base radically for the election next May. Some in the Fine Gael leadership would prefer to run Mayo TD and GAA strongman John O'Mahony instead, alongside MEP Mairéad McGuinness.

But Mr Higgins is having none of it. He acknowledged there were “all sorts of conspiracy theories out there” but insisted he did not share them.

The election will be difficult, too, for former Labour MEP Nessa Childers, now an Independent in the East constituency. Her core constituency base has been cut by a quarter and enlarged by much more than that but she has no regrets over leaving the party fold over budget cuts.

“I didn’t make it easy for myself, but there are more important things than being in a political party,” she said.