Democratic Unionist Party leader Ian Paisley is to stand down as a Member of the European Parliament ahead of the next elections in June, the BBC has learned.
Mr Paisley has held the seat since its inception in 1979
Mr Paisley, the North Antrim MP and assembly member announced his retirement from European politics on Monday.
The 77-year-old has said he wants to devote more time to leading his party's negotiating team in the forthcoming review of the Good Friday Agreement, which begins on 3 February.
The devolved administration at Stormont was suspended in October 2002 amid allegations of IRA intelligence-gathering in the Stormont government.
The DUP overtook the Ulster Unionists to become the biggest party in the assembly following elections last November.
The party has 33 assembly seats and six MPs, following the defection of Ulster Unionist MP Jeffrey Donaldson.
"We have been accused of not being serious about these talks," said Mr Paisley.
"Well, we are serious about these talks.
"Because of this I am not running away from Europe. I'm going to finish my
course there. But I am not going back to Europe.
"I am going to be here in Northern Ireland. I am going to be in every one of these talks. Bertie Ahern will get away with nothing."
Dr Paisley has held his seat in Europe since it inception in 1979.
He topped the poll at each election for the constituency's three seats.
BBC Northern Ireland's political correspondent Gareth Gordon said many would interpret Mr Paisley's decision as "the first sign that one of the major figures of the Northern Ireland political scene for more than 40 years is now contemplating the day when he must hand over the party to a younger leader".