McGuinness last week confirmed she will contest the Louth constituency where Fergus O'Dowd is the sitting Fine Gael TD. Fine Gael believes the party can win two seats in Louth, with Séamus Kirk of Fianna Fáil being vulnerable, although the party has never elected more than one TD in the four-seat constituency.

McGuinness won almost 115,000 first-preference votes in the 2004 European elections. If she takes O'Dowd's Dáil seat, she would have to resign as an MEP.

This move would benefit another member of the O'Dowd family.

Michael O'Dowd, a councillor in Drogheda, is the first named replacement candidate for McGuinness should she resign as MEP. He admitted this weekend that he was placed in a "unique position" but was unwavering in his choice of candidate to support.

"My position is very clear. I will be a valuable member of Fergus's team in trying to get him re-elected, " he said, adding that the contest in Louth would be "a very difficult battle as the percentages speak for themselves."