He was a member of the Legislative Assembly of Ontario from 2003 to 2007 representing the Greater Toronto Area riding of Mississauga South.
[2] The Liberals under Dalton McGuinty formed a majority government and Peterson was named parliamentary assistant to Jim Bradley, the Ontario Minister of Tourism and Recreation.
[3] In 2006 he was appointed as parliamentary assistant to George Smitherman, the Ontario Health and Long-Term Care.
Minister of Finance Greg Sorbara said, "It's just common knowledge around our caucus that Tim has been disappointed for quite some time about the role he had been assigned within our government.
Former Mississauga South PC MPP Margaret Marland called the process "despicable".