A new Ipsos-Reid poll suggests almost half of Canadians see a party's stand on same-sex marriage as affecting how they'll vote.

We just don't know how.

"The potential for supporting or opposing it is equally in play," pollster John Wright, the firm's senior vice-president, told CTV.ca.

Those most likely to vote against the Liberal government on same-sex marriage will likely support the Conservatives, he says.

"But their (the Tories') points only rise to 29 per cent of the vote," he says. Those voters tend to be older.

"There is a constituency, however, that wants to go to the polls on this. They tend to be more urban, female and younger, who in fact welcome this and would vote for the government."

In polling conducted by Ipsos-Reid a few weeks ago, if a federal election was held in which same-sex marriage were the main issue, the governing Liberals would get 41 per cent of the vote. The Conservatives would get 29 per cent and the NDP 13 per cent. In Quebec, the Bloc Quebecois would get 36 per cent.

In the poll released Monday, the Liberals have 37 per cent support, the Conservatives 26, the NDP 17 and the Bloc Quebecois 10 per cent nationally.

"This is just one more part of the volatile mix," Wright says.

Parliament has started dealing with the issue in earnest. The Liberals introduced their legislation, which aims to give gays and lesbians the right to civil marriages, earlier this month. Prime Minister Paul Martin and Conservative Leader Stephen Harper kicked off debate last week.

For the Conservatives, the same-sex marriage issue "might play to their short game but it doesn't play to their long game," Wright says.

"It continues to provide a perception of the Conservatives as being more parochial social conservatives, more western-based, and it doesn't break them out of the box that they need to actually get some healthy seats."

Wright says he's been doing polling on Canadians' attitudes towards same-sex marriage for about four years now.

"The numbers have not changed," he said, noting it's roughly 55-45 in favour.

Those completely dead-set against it tend to be from Saskatchewan, Manitoba or Alberta and account for just under 30 per cent of the total opposition. For the Conservatives, those areas of Canada are where they already elect the vast majority of their MPs.

They need to make breakthroughs in Ontario and Quebec to form a government. In Ontario, there is a "blue belt" where same-sex marriage could drive up to 15 seats to the Tories, he says.

Asked if the Conservatives' same-sex strategy was just hardening Conservative support rather than breaking chunks away from the Liberals, Wright says, "That's a good hypothesis."

While the Conservatives gain about three percentage points of support on the same-sex issue, "the last time I checked, they have to picking up 10 or 12 points in order to get them into the range to form any kind of government, and it simply hasn't happened," he says.

If one looks at the bigger picture, the Liberals are still the leading party in Canada even though they've had a number of problems to deal with.

"I don't think it's going to play out as significantly as Conservatives suggest it will," Wright says, adding the Liberals' defence of the Charter of Rights and Freedoms as their strategy for "selling" same-sex marriage may well appeal more to immigrant communities.