Top Irish republican Gerry Adams will quit the Northern Ireland Assembly to fight for a seat in Ireland's next general election, party sources said on Sunday.
The Sinn Fein president was expected to make a formal announcement later on Sunday at 1500 GMT.
Adams will seek the nomination for County Louth, which lies south of the border with Northern Ireland. However, he will keep his West Belfast seat at Westminster in London.
County Louth's sitting member of parliament, Arthur Morgan, has decided last week not to run for Sinn Fein in Ireland's next general election, which must take place by 2012.