Kerry Senator Mark Daly has been sacked from his role as deputy leader in the Seanad by his party leader Micheal Martin.
The decision comes after Mr Daly and Galway West TD Eamon O Cuiv participated in an apparent launch of a party candidate in Northern Ireland last month.
Mr Martin has replaced Mr Daly as deputy leader with Fingal based senator, Lorraine Clifford Lee.
Senator Ned O'Sullivan has also been given responsibility for Foreign Affairs, the Irish Overseas and Diaspora.
The news was confirmed by way of a statement this morning.
“Deputy Martin has wished both senators well in their new roles,” the statement added.
Mr Martin has moved to discipline Mr Daly and it is expected Mr O Cuiv, a former deputy leader of the party, will face a similar sanction. He is currently Fianna Fáil frontbench spokesman on rural affairs.
Mr Daly has told the Irish Examiner: "I accept the decision of the leader and I will continue to work hard on behalf of my constituents.
"In my position as Foreign Affairs spokesperson for the last number of years, I have worked closely with John Deasy TD in his role as the Government’s US Envoy, our party spokespersons on Foreign Affairs, members of the US Congress, as well as the White House on the proposed visas for Irish citizens.
"I have been working closely with all sides and hope to continue to assist in this important issue and if necessary go to DC, as we work to reach an agreement in the coming weeks."
Last month, Mr Ó Cuív and Mr Daly were photographed attending the election launch of councillor Sorcha McAnespy, who is an independent councillor in Fermanagh.
The two men were pictured with Ms McAnespy alongside Fianna Fail branded election posters only for party headquarters to issue a statement to insist no decision had been taken as to whether it would contest elections in the North.
“It follows then that it has selected no candidate to contest these elections,” a statement at the time added. “Discussions between the party and the SDLP are ongoing and a statement on our future intentions will be made in due course.”
Fianna Fáil and the SDLP have been in discussions about a possible merger but those talks have not concluded.