Dec. 7 (Bloomberg) -- Canadian Prime Minister Stephen Harper, whose Conservative Party lacks a majority of seats in Parliament, lost a vote today to revisit a 2005 law allowing same-sex marriages.

The government's motion was defeated by a margin of 175 to 123, House of Commons Speaker Peter Milliken said in Ottawa today. Harper's Conservatives have 124 of the 308 House of Commons seats. While the leaders of all three opposition parties opposed the motion, Stephane Dion of the Liberal Party allowed his 101 members to vote according to their consciences.

Harper, 47, promised to hold a vote on the issue before he was elected in January, a pledge that boosted his support among social conservatives. If the motion had passed, Harper pledged to introduce a law to ``restore the traditional definition of marriage while respecting existing same-sex marriages.''

Harper called today's vote ``decisive'' and told reporters his government ``will accept the democratic result.'' He said he doesn't plan to reopen the file again.

Lawmakers voted to legalize same-sex marriage in June of last year by a margin of 158 to 133, when Harper was opposition leader and Paul Martin of the Liberal Party was prime minister. Last year's vote didn't reflect the will of Parliament because Martin forced some of his legislators to vote for the law even though they personally opposed it, Harper has said.

Belgium, the Netherlands, South Africa and Spain have also legalized same-sex marriages, according to Canada's justice department.

About 12,400 same-sex marriage licenses have been granted in Canada since the province of Ontario legalized them in June 2003, according to Canadians for Equal Marriage, a gay-rights organization.

To contact the reporter on this story: Greg Quinn in Ottawa at gquinn1@bloomberg.net.

Last Updated: December 7, 2006 15:48 EST