All declared candidates for leadership of the federal Conservatives will march in Toronto's gay Pride parade Sunday — a historic first for a party that has struggled in its position on LGBT rights.

Kellie Leitch, Michael Chong and Maxime Bernier will join members of LGBTory Canada, an advocacy group that championed overturning the party's traditional definition of marriage. That change to the party's constitution, enacted at the party's convention in Vancouver, is just part of a recent Tory shift on gay rights.

"I think the leadership candidates want to send a message that they're turning the page on these divisive social issues," Eric Lorenzen, an executive member of LGBTory, said in an interview with CBC News. "I think that the party is trying to portray a more inclusive, tolerant and diverse face to the public. We don't have to be quiet about these issues anymore. It's OK to march."

Lorenzen said there's a markedly different tone on LGBT issues since the party's defeat last October, and the same-sex marriage vote in May, calling this year a turning point.

The party has never been a monolith — Conservative MPs and cabinet ministers broke ranks with former prime minister Stephen Harper and his push to reverse same-sex marriage legislation — but gay Conservatives are now being embraced by leadership candidates as an important constituency, said Jamie Ellerton, who was part of LGBTory in its infancy.

Delegates at the Conservative Party's convention in May voted to change the wording of the traditional definition of marriage in the party's constitution. (Jonathan Hayward/Canadian Press)

"I think it's an evolution of Conservative principles … society has moved quite far on [gay rights] and so has the Conservative Party. It doesn't get the credit it deserves," Ellerton said, noting Harper never reopened the debate on marriage after the free vote and former immigration minister Jason Kenney welcomed gay refugees from countries where repression of sexual diversity is rampant.

"Just because you're gay doesn't mean you're a tax and spend socialist," he said.

'Big blue tent'

Interim Conservative Leader Rona Ambrose has branded her party as a big blue tent open to all, regardless of who they sleep with or how they identify.

"If you believe in smaller government, lower taxes, balanced budgets and individual freedom, we want you in our party," Ambrose said ahead of the convention vote on marriage.

Moreover, a recent opposition day motion, backed by Ambrose, calling on the government to condemn ISIS as a perpetrator of genocide, explicitly mentioned the atrocities the group committed against gay people who have the misfortune of living in its so-called caliphate.

Many members of Ambrose's shadow cabinet have publicly championed gay marriage, even as one member of their caucus, Brad Trost, branded it as a sort of socialist plot.

"The language of equality and comparisons, to me that's socialist language, the way they do it," Trost said. "The same way they talk about equality of income, where they want to tax from the rich to bring them down to the level of the poor."

Another Conservative MP, Ted Falk, recently balked at attending a Pride parade in his Manitoba riding, saying he is standing by his "values of faith, family and community."

Tory MPs Michelle Rempel and Brad Trost speak to reporters at the party's sonvention in Vancouver after delegates show support for move to cut one man/one woman marriage definition from party's policy book. 1:09

"It just shows that there's still work there to do to change the hearts and minds of some people," Ellerton said of the strident social conservatives in the party's mix. "The vast majority are accepting of these things … just because some fringe elements will continue to be out there doesn't mean we should give up on them."

Lorenzen said that some social conservatives have come forward since the convention to complain that there isn't a role for them in the party after the same-sex marriage vote.

"Our message to social conservatives is: We don't want to silence you, we just don't want you to silence us," he said.

Trudeau will be 1st PM at Pride

The more vocal Tory support comes as the government in Ottawa positions itself as a champion of gay rights both at home and abroad.

Justin Trudeau, who last year launched his election campaign at Vancouver Pride, will also be at Sunday's march in Toronto — a first for a sitting prime minister.

He has raised the rainbow flag over Parliament Hill and pushed for the appointment of an independent expert at the United Nations on preventing violence based on sexual orientation. His closing speech at the Three Amigos conference in Ottawa this week also started with a pledge to do more to stop discrimination against the LGBT community in North America.

Trudeau raises the Rainbow flag on Parliament Hill for the first time 1:17

However, his government has so far failed to fully overturn restrictions on blood donations by men who have sex with men, despite a campaign pledge to do just that.