The Fianna Fáil general secretary, Mr Martin Mackin, is to step down from his position to pursue a fellowship in the US.
Mr Mackin will begin a three-month fellowship at the Institute of Politics at the John F. Kennedy School of Government at Harvard University next month.
Yesterday, Mr Mackin said he felt it was a bit of an honour to be offered the fellowship. "I am not sure what I'll be doing when I come back but it will be something in the broad area of public affairs and politics," he said.
Mr Mackin has been the party's general secretary for five years. He began working for Fianna Fáil as a press and research officer in 1992, then worked with the party's group in the European Parliament.
In addition to his work on the recent Nice referendum, and last year's general election campaign, he played a central role in 1997's general election and presidential election campaigns.
Yesterday, the Taoiseach, Mr Ahern paid tribute to Mr Mackin, saying he had presided over a time of great change.