Noel Dempsey was born in Trim, County Meath in January 1953. He was educated in Trim and at University College Dublin and he qualified as a career guidance counsellor. Since 1977 Dempsey has been involved in local politics with Meath County Council. In 1987 he was first elected to Dáil Éireann and has retained his seat at every election since. In 1991 he came to national prominence when he became one of four Fianna Fáil backbenchers to call for the resignation of Charles Haughey as Taoiseach. Dempsey stated that he was vehemently opposed to the coalition between Fianna Fáil and the Progressive Democrats.
Between 1992 and 1994 he became Government Chief Whip and Minister for State at the Departments of an Taoiseach, Defence and Finance. Dempsey became embroiled in a public disagreement with the Minister for Arts, Culture and Heritage regarding plans to build a number of interpretative centres in environmentally sensitive areas around the country. In 1997 Dempsey joinmed the Cabinet when he was appointed Minister for the Environment and Local Government. He also helped in the negotiations for thew formation of the coalition government. In 2002 Dempsey became Minister for Education. In early 2003 Dempsey revealed his political ambition when he announced that should the position become available he would seek the leadership of the Fianna Fáil party and the Taoiseachship.