Former Ottawa mayor Bob Chiarelli is launching a campaign to become the Liberal nominee to represent Ottawa West-Nepean at the provincial level.

The seat is being vacated by Jim Watson, who stepped down from his cabinet post last week to run for mayor. Watson is expected to resign from his responsibilities as MPP for the riding within the next few weeks.

Premier Dalton McGuinty has up to six months from receiving Watson's official resignation to call a by-election in the riding.

Chiarelli is hoping to capitalize on Watson's departure, saying he's confident his experience will help secure him a seat with the Liberals at the provincial legislature.

"I'm certain with my experience -- nine years at city hall and 10 years at Queen's Park -- that I have the skills set and I know that I have the commitment to make a positive difference," Chiarelli said on Monday.

"I know that I will be a positive bridge between Queen's Park and the City of Ottawa."

Chiarelli previously held the seat in Ottawa West-Nepean for the Liberals from 1987-1997.

He then became regional chair of Ottawa-Carleton in 1997, later becoming mayor of Ottawa for two terms. He was defeated in the 2006 municipal election by current Ottawa Mayor Larry O'Brien.