Sinn Fein president Gerry Adams has resigned from his Westminster seat.
The announcement came after Taoiseach Brian Cowen confirmed March 11 as the date for the Irish Republic's General Election.
Mr Adams had already stepped down from his West Belfast seat in the Northern Ireland Assembly.
He had also pledged to resign as Westminster representative for the same constituency when a poll was confirmed south of the Irish border.
A party spokesman said the process had now started and confirmed Mr Adams had written to Westminster to formally resign.
The Sinn Fein president will now stand for the Republic's Dail parliament in the border area of Louth.
Mr Adams's move comes as his all-Ireland party hopes to make gains in the south.
He was replaced at the Assembly by former IRA hunger striker Pat Sheehan.
The party will now select a candidate to defend his west Belfast Westminster seat.
Sinn Fein refuses to take seats in the House of Commons, but Mr Adams hopes he will soon be sitting in the Dail alongside party colleagues.