He is expected to make an announcement ‘in the next few days’ according to close friends.
If he does quit – and the former Mayor has confirmed he is ‘considering my future in Fianna Fail’ – it would be a major blow to the party.
He was director of elections in the general election in Donegal South West where a two candidate strategy backfired with Mary Coughlan and Brian O Domhnaill failing to land a seat.
Instead independent Thomas Pringle won out.
A close friend of Byrne told donegaldaily.com: “Brendan is very unhappy with Micheal Martin and Eamon O’ Cuiv and their decision not to field a candidate for the party. He can’t stay in a party that is being so defeatist.”