Sinn Féin's Martin McGuinness is to resign his Westminster seat.
The MP for Mid-Ulster will remain as an MLA in the Stormont Assembly and Deputy First Minister.
The move comes as his party seeks to end ''double-jobbing''.
Sinn Féin also announced today that four MLAs are leaving their posts.
Sinn Féin President Gerry Adams said the party's four other MPs will stand down from the Northern Ireland Assembly where new representatives can be put in their place without further elections.
Mr Adams said his party would continue to refuse to sit in Westminster, but wanted to avoid creating a string of electoral contests by resigning all five of its parliamentary seats.
Stormont politicians have been heavily criticised in the past for holding posts in local councils, the devolved Stormont Assembly and at Westminster.
Mr Adams said: "The key thing to be said about this issue is that other parties are talking about ending dual mandate, Sinn Féin has ended dual mandate."
Pat Doherty will leave his position as West Tyrone MLA.
Elsewhere, Paul Maskey will vacate his West Belfast seat.
Meanwhile, Michelle Gildernew will be replaced in the Fermanagh and South Tyrone constituency and in Newry, while Conor Murphy will leave his post in Armagh.
They will be replaced by co-opted Sinn Féin members.
Separately, Martin McGuinness said it would be a huge ask on the part of any Irish Republican to meet Britain's Queen.
She is due at a garden party at Stormont later this month to mark her diamond jubilee, and there has been speculation that Mr McGuinness might meet her.
He said the way in which the Northern Ireland Office had announced the Stormont event without consulting his party had been insensitive.
Mr Adams said the party had no intention at present of meeting the Queen.