MacDonald served as mayor of Sydney, Nova Scotia from 1978 to 1993.[2] He entered provincial politics in the 1993 election, defeating Peter Mancini and Norm Ferguson to win the Cape Breton South riding.[3] MacDonald served as a backbench member of John Savage's government until June 27, 1996, when he was appointed to the Executive Council of Nova Scotia as Minister of Labour.[4]
When Russell MacLellan was sworn-in as premier in July 1997, MacDonald was named Minister of Economic Development and Tourism.[5] In 1997, he also took over as the Liberal House Leader, a position he held until January 2012.[6] In the 1998 election, MacDonald was re-elected by over 2,600 votes.[7][8] Following the election, MacDonald remained at Economic Development and Tourism, but was given six other portfolios in the minority government, including the Priorities and Planning Secretariat, and responsibility for Sysco.[9] In December 1998, he was given an additional role in cabinet, Minister responsible for the Petroleum Directorate.[10]
The Liberals lost government in the 1999 election, but MacDonald was again re-elected in his riding by over 2,000 votes.[11] Moving to the opposition side for the first time in his career, MacDonald was re-elected in the 2003,[12] 2006,[13] and 2009 elections.[14][15]
On January 6, 2012, MacDonald announced he would be retiring from politics prior to the next provincial election.[2][16] In May 2013, MacDonald came under scrutiny for taking a four-week holiday during the spring session of the Nova Scotia Legislature.[17] He resigned his seat on May 29, 2013, one day before a scheduled vote of the legislature on whether to dock his pay for the time he was absent.[18][19]