RN Collection: Mary Lou McDonald. Sinn Fein Vice President, Mary Lou Mc Donald, will be elected as the new leader and President of sinn Fein, to succeed Gerry Adams, in February 2018. End. 18/11/2017. Sinn Fein Ard Fheis. Party President Gerry Adams beforespeaking during his Presidential Address at the Sinn Fein Ard Fheis in the RDS In Dublin today. In front of him are L TO R Conor Murphy with Deputy leader Mary Lou MCdonald and He confirmed he will step down as leader next year and will not contest the next Dail election. Photo RollingNews.ie