MONTREAL - It's a celebration of past Conservative majorities, but it's unclear whether a gala Thursday honouring Brian Mulroney might help pave the way for future ones.

A 25th anniversary party for Mulroney's 1984 election landslide is being cast by members of the Harper government as a show of unity for a party that recently suffered its share of discord.

The guest list includes Prime Minister Stephen Harper's wife, Laureen, and more than 20 current MPs from both the old Reform and Progressive Conservative wings of the current governing party.

Relations became strained between Mulroney loyalists and the government over the past year amid an inquiry into the former prime minister's business dealings.

Mulroney's allies have frequently cited that spat as a reason the party did so poorly in Quebec, and lost its shot at a majority in last fall's federal election.

But observers say it's questionable that the display of unity in a downtown Montreal hotel Thursday night might actually make a difference.

One well-connected political commentator compares the party to a high school reunion involving greying politicians of days gone by.

"There's a new generation of players in the Tory party. Those active 25 years ago, they had power then but most of them now are members of the golden-age club," said Jean Lapierre, a former federal Liberal cabinet minister and onetime Bloc Quebecois MP.

"It's a party of old party hacks. It's nice to see them but, at the end, you're not talking about a force that can change the dynamics of politics in Quebec. You're talking about people 25 years ago who had some influence."

A pair of former Mulroney cabinet ministers - Quebec Premier Jean Charest and outgoing U.S. ambassador Michael Wilson - will co-host the gathering.

One of Mulroney's closest friends laughs when asked whether there's any horsepower left in the vaunted political machine that twice steamrollered Quebec.

"Quite a few of them have died but there are still some old-timers that are still active in the party," said Bernard Roy, Mulroney's former chief of staff. He cited Sen. Pierre Claude Nolin as one Mulroney loyalist still active.

Roy says the political landscape has changed - especially in Quebec - since Mulroney's heyday. At the time, there was no Bloc Quebecois siphoning off anti-Liberal votes in the province.

Key to Mulroney's success was his ability to attract members of a coalition that included Quebec nationalists, committed sovereigntists, and prominent labour leaders. Among them was Lucien Bouchard, who sat in Mulroney's cabinet before they had a spectacular falling out.

Bouchard went on to found the Bloc.

All these nationalists joined Mulroney for what then-PQ premier Rene Levesque dubbed "the beau risque" - the effort to end Liberal rule, and seek reconciliation between Quebec and a new federal Conservative government.

"The old saying that politics makes for strange bedfellows, I would say that applies very much to what was done in '84," Roy said.

Mulroney grabbed 58 of Quebec's 75 seats in 1984, winning what many consider the biggest landslide in Canadian history.

Roy says he'll be in Europe during the gala but that he's recorded a video message for Mulroney. The Canadian Press has learned Harper will also deliver a videotaped message in a clear sign of attempted bridge-building.

Organizers of Thursday's bash say it began simply as a way for old friends, colleagues and supporters - members of a Facebook fan club were among those invited - to get together to reflect on Mulroney's accomplishments.

The guest list has since swelled to 700 and the gala is poised to become one of the biggest Tory events of the year.

"It wasn't difficult to find people," Charest told The Canadian Press on Wednesday.

"And it's way beyond Conservatives (coming) - (it's) people from every walk of life who just want to salute and acknowledge Mr. Mulroney and the fond memories we have of that election 25 years ago and then the government that followed."

The $100-ticket charitable event wasn't organized by the Conservative party. Still, some 20 current MPs, including Peter MacKay, Jim Flaherty, John Baird, Jay Hill, Rona Ambrose and Diane Ablonczy, are expected to attend.

Insiders call the event a sign of a shift in approach from Harper, who famously forbade his caucus from speaking with Mulroney during the recent Oliphant inquiry.

Some Tories, especially those close to Charest and Mulroney, had complained Harper put too much faith in the now-flailing Action democratique du Quebec while ignoring traditional Progressive Conservative allies in the province.

"It's time to change strategy and open up and include more Mulroney people, who actually delivered votes in Quebec and a lot of seats," said one Tory.

"I think if (Liberal Leader Michael) Ignatieff is watching this, he better be careful," another said.

Still, not everybody's convinced a night of shmoozing will make a difference for the Tories.

McGill University political scientist Antonia Maioni believes the Tory-ADQ alignment and Harper's decision to distance himself from Mulroney created a deep divide.

The party, she said, remains a turbulent marriage between PCs and Reformers and she doubts the camps will be able to completely "bury the hatchet" in the near future.