Opponents and supporters of same-sex marriage are lobbying MPs on Parliament Hill Tuesday as the Harper government prepares for a free vote on the issue, expected later this year.

About a dozen religious and social conservative groups that call themselves the Defend Marriage Alliance are holding a full-day "national marriage caucus" in Ottawa, with press conferences, private meetings with MPs and public rallies.

Charles McVety, president of the Canada Family Action Coalition, wants MPs to study marriage before holding a free vote.
(Fred Chartrand/Canadian Press)

In response, groups in favour of same sex marriage laws, including some religious organizations, are also on Parliament Hill to explain their positions.

One of the leading opponents of gay marriage, Charles McVety, president of the Canada Family Action Coalition, says the idea is to "address MPs face to face and ask them at least to study marriage" before holding the free vote. 

Not enough 'true debate': McVety

Bill C-38, McVety said, was passed hastily and without proper study.

"There was never true debate, true discussion," he said in an interview with CBC Newsworld. "Why don't we simply study the impact of this [Bill C-38] on the age-old institution of marriage."

McVety said the legislation posed dilemmas for marriage commissioners who were themselves opposed to same-sex unions but had to carry them out by law, and to teachers, who were expected to guide children on matters of sexuality and human relationships.

But supporters of same-sex unions say the issue has been studied repeatedly and that opponents of C-38 are trying to keep alive an issue that most Canadians consider closed.

"The religious right wants to reopen this issue, delay the vote and drag things on for years," said Laurie Arron of Canadians for Equal Marriage. "Unfortunately our prime minister, Mr. [Stephen] Harper, seems to support them."

Same-sex marriage became legal in Canada last year when Parliament passed Bill C-38 in response to a series of court rulings that gay people had the right to marry.

But Harper promised during last January's election campaign to reopen the issue and allow a free vote that could overturn the legislation. A parliamentary vote is expected before December.

Polls show that most Canadians either support same-sex marriage or don't want a divisive debate on the issue. There are some 10,000 gay couples who have married since Bill C-38 was passed.