FACTBOX: Profiles of two main party leaders in Canada

(Reuters) - Here are profiles of Canadian Prime Minister Stephen Harper and Stephane Dion, the leader of the official opposition Liberal party, one of whom is likely to win Tuesday's election.

Stephen Harper, 49:

* Prime minister since his Conservatives -- which dominate in Canada's Western regions -- won a minority government in the January 23, 2006, election.

* Started off as a legislator for the Western-based right-wing Reform party between 1993 and 1997 but quit after policy differences with the party leadership.

* Headed the conservative National Citizens Coalition lobby group between 1998 and 2002.

* Became leader of the Canadian Alliance party -- the successor to the defunct Reform party -- in 2002. Pushed through a union of the Alliance and the Progressive Conservative Party in 2003 to create the Conservative Party. He was elected party leader in March 2004 and lost an election to the Liberals in June that year.

* His stiff manner is often the butt of jokes. He is an avid ice hockey fan and is writing a history of the game.

* Born on April 30, 1959; married with two young children.

Stephane Dion, 53:

* Surprise win in the December 2006 Liberal leadership race, beating more experienced candidates with a platform that stressed the need to protect the environment.

* Served as federal environment minister in the Liberal government from July 2004 to February 2006.

* Served as Liberal minister of intergovernmental affairs from 1996 to 2003, where he was best known for his battles with separatists in the French-speaking province of Quebec. In 2000 he pushed through the so-called Clarity Act, making it much harder for Quebec to secede. The move helped preserve Canadian unity but made Dion unpopular among many people in his home province.

* Before he entered politics he was a political scientist in Quebec, where he developed his opposition to the idea of Quebec separatism.

* Speaks a heavily French-accented English.

* Born on September 28, 1955; married with one daughter. His pet Husky is called Kyoto, named after the international agreement on climate change.

(Reporting by David Ljunggren; Editing by Eric Walsh)