The Fine Gael TD Mr Michael Ring has said he will not appeal the High Court ruling last month upholding legislation abolishing the so-called dual mandate.
Mr Ring, who has served on Mayo County Council for 25 years and has never lost his seat, will now not stand for re-election to the local authority in the June local elections.
Last month, he lost his challenge to new legislation which prevents members of the Oireachtas from also serving on local authorities.
Ms Justice Laffoy, in a reserved judgment, said the central plank of Mr Ring's case was that he had a constitutional right to stand for election to Mayo County Council. However, she found, there was no constitutionally guaranteed right to stand for election to a local authority.
The TD said today he could not afford the cost of taking an appeal to the Supreme Court.
"I'm not a millionaire, I don't have a second salary and I wouldn't put my family through it," he told ireland.com.
The Mayo TD failed in his bid to get part of his costs awarded in the High Court
case and he estimates it would cost up to €80,000 to take an appeal to the Supreme Court.
"It would be unfair to my family and my own future to gamble with the huge sum of money that would be involved in an appeal," he said.
"It is a sad day when murderers and rapists and tribunalists can have free access to the courts but if I want to contest an important issue of law that is basic to my democratic freedom, I am squeezed out because of cost.
"It is a terrible thing that the people could elect me for 25 years and now the Oireachtas and the courts are denying me the right to stand for election," he said in a statement.
Mr Ring said he would not resign from Mayo County Council but would serve out his term of office until the council is dissolved next June.
He said the process of electing a candidate to contest the election on behalf of Fine Gael in Westport would now get underway.
However, he ruled out the possibility that any family member, including his brother, would run for election, saying he would not wish his family to become involved in politics.
Mr
Ring, an auctioneer by profession,
was first elected to the Dail in a by-election 10 years ago following the resignation of Mr Padraig Flynn, who became an EU Commissioner.