When former premier Mike Harris resigned as the member for Nipissing in early 2002, McDonald won the Progressive Conservative nomination to replace him.
In a by-election held on May 2, 2002, he defeated Liberal candidate George Maroosis, also a city councillor, by 19 votes, as confirmed by a recount.
[3] In the federal election of 2004, McDonald ran for the Conservatives in the redistributed riding of Nipissing—Timiskaming, but lost to Liberal Anthony Rota by 2,253 votes.
[4] On August 26, 2010 McDonald announced his intention to run for mayor of North Bay in the 2010 municipal election.
[5] He won 87 per cent of the vote on election day over challengers Valerie Chadbourne and Harvey Villneff.