Jim Watson, the Ontario municipal affairs and housing minister, was mayor of Ottawa from 1997 to 2000. (www.jimwatsonmmp.ca)

Ontario Municipal Affairs and Housing Minister Jim Watson wants to be Ottawa's mayor again, CBC News has learned.

A source close to the Liberal MPP for Ottawa West-Nepean confirmed that Watson will announce his candidacy Tuesday morning.

In a year-end interview with CBC News, Watson had been non-committal when asked if he had designs on the mayor's seat that he held between 1997 and 2000.

Coun. Alex Cullen and Robert G. Gauthier, former publisher of the independent newspaper National Capital News, have already announced their candidacies for the job.

"He is going to have a major impact on this race due to his personality," Cullen said, when asked about the possibility of Watson's candidacy, before adding: "Style is nice, but it's substance that counts."

"What will Jim Watson bring in terms of where we go with light rail, where we go with our infrastructure, or sewage going into the Ottawa river, where we go with our funding for community programs, arts programs? And those are the substantive issues."

Mayor Larry O'Brien has not revealed whether he will seek re-election.

Watson would have to step down from his provincial cabinet position to run a mayoral campaign.

His decision comes amid persistent rumours that Premier Dalton McGuinty will be making dramatic changes to his cabinet. McGuinty already has to replace former deputy premier George Smitherman, who resigned as a member of the provincial parliament last week to run for mayor of Toronto.