In an age of campaigns fixated on social media and driven by ads aimed at thin slices of the electorate, making a big deal out of filling a room with sweaty partisans shouting themselves hoarse might seem laughably outdated. And yet in 2011, it was a Jack Layton rally at Montreal’s gilded old Olympia Theatre—the biggest NDP campaign event ever in Quebec—that definitively drew national attention to what turned into his “Orange Wave” breakthrough in the province. When accounts of the 2015 election are written, Liberals hope Justin Trudeau’s massing of supporters in a hockey arena in Brampton, Ont., last Sunday will acquire similar status, not as a turning point, exactly, but as the moment when the real possibility of sweeping change came into focus.

More than 5,000 Liberals packed the Powerade Centre, home of the minor-league Brampton Beast, for the event. Trudeau delivered a rousing speech, framing the choice as being between his Liberals’ “confident and hopeful” approach and “talk of fear” from Stephen Harper’s Conservatives. He didn’t just present that broad-strokes contrast, though. Speaking to a crowd visibly representative of the big immigrant populations in many ridings up for grabs around Toronto, Trudeau zeroed in on Harper’s use, during one of the televised leaders’ debates, of the term “old stock” for Canadians who have been in this country for generations. “In 10 years, Stephen Harper has never missed an opportunity to divide Canadians,” Trudeau said. “East against west, urban against rural, French against English, so-called ‘old-stock’ Canadians versus newcomers.”

The roar of umbrage that greeted that line was perhaps the most intense of the evening. It served as a reminder that Trudeau’s bid to recover ground the Liberals have lost to the Conservatives among immigrants and their children is arguably his top strategic aim in this campaign. After all, of the 23 new seats the Tories picked up in 2011 to win Harper’s first majority, 20 were in and around Toronto, all of which had at least 30 per cent immigrant populations, and eight of which were majority immigrant. Harper’s ability to attract newcomers’ votes was suddenly the envy of conservatives struggling to make inroads in fast-growing “cultural communities” in Europe and America. Interviewed in New York last fall by the Wall Street Journal’s editor-in-chief, Harper boasted that his Conservatives had become “the majority party” among ethnic voters. “So that’s been the big transformation of politics in our country,” he said.

There’s no doubt that steady Conservative advances among traditionally Liberal-voting new Canadians was a major factor in the past several elections. This campaign, though, is turning into a test of whether or not that change is deeply rooted. Among the major figures in Trudeau’s push to prove that the Tories’ success in courting immigrants was transient is his Ontario co-campaign chair, Navdeep Bains, a Sikh whose Liberal-red turban made him one of the most instantly recognizable MPs in the House from 2004 until 2011, when he lost his suburban Toronto seat.

Unlike that disastrous campaign under Michael Ignatieff’s leadership, Bains says this time out Liberals have an appealing pocketbook pitch to make. He says two Liberal platform centrepieces—a new Canada Child Benefit for parents and a middle-income tax cut, to be paid for by hiking taxes on earnings over $200,000—are an easy sell on the suburban doorstep. The average household income for a family of four in Mississauga–Malton, the newly created riding where Bains is now running, is around $90,000—right in the sweet spot for that Liberal tax-and-benefits package. “Not only do we knock on doors to talk about change, we have specific policy points to talk about that really resonate,” Bains says.

But Harper is fighting back with his own appeal to economic concerns felt acutely in much of the Toronto region. Earlier this week, he was in Whitby, just east of the city, at a plant that makes vehicle emissions control parts, to announce $1 billion in extended federal support for automotive innovation. That injection of long-term funding is a crucial part of the Conservative bid to reassure voters, especially in Ontario’s manufacturing heartland, that the newly negotiated Trans-Pacific Partnership—a 12-country trade deal that will cut tariffs—won’t decimate auto parts makers.

Beyond soothing sectoral anxieties, Harper is positioning joining the new TPP trade zone as a reminder of his government’s record for economic management. “Ten years from now,” he said, “I predict with 100 per cent certainty [that when] people are looking back, they will say—if we’ve got in it—they’ll say that was a great thing.” Trudeau voiced support for the trade pact in principle, although he withheld full approval until he sees the complete text. Tom Mulcair came out firmly against the deal, citing the risks to jobs at auto parts companies in southwestern Ontario, where his NDP is hoping to pick up perhaps half a dozen seats, and to dairy farmers, especially in Quebec, where he is trying to safeguard Layton’s 2011 breakthrough.

Beyond downtown Toronto, where NDP candidates are locked in tight contests with Liberals, Mulcair seems to be focusing on only a handful of potential new Ontario seats. By contrast, the Liberal path to victory relies on scoring Ontario gains by the dozens. John Wright, senior vice-president of the polling firm Ipsos Reid, said the race is so close now between the Conservatives and Liberals in more than 30 ridings near Toronto that even what might appear to be slight shifts in the vote between the two parties could be definitive on Oct. 19. His ﬁrm’s latest online survey, conducted Oct. 2-5, found the Liberals ahead with 45 per cent support in the 905 area code zone around Toronto, with the Tories close behind at 42 per cent and the NDP far back at 11 per cent. “If you were to shift five per cent of the population in Atlantic Canada, say, it’s not going to make that much difference, because there aren’t as many seats,” Wright said. “You shift over five per cent of the voting population in the Toronto area, it makes a huge difference.”

As recently as June, the pollster noted, Conservative support was so strong in the Toronto suburbs that Harper’s strategists might reasonably have expected to dominate there again. But the Liberals steadily closed the gap and then passed them, while the NDP’s failure to gain traction has diminished the likely impact of left-of-centre vote-splitting that helps the Tories. And, as Trudeau has built support nationally through the campaign, immigrant voters around Toronto have, broadly speaking, followed the Canadian trend.

That pattern is in line, according to University of Toronto political science professor Christopher Cochrane, with recent academic research that has tended to ﬁnd Canada’s immigrant voters less distinctive than previously thought. “One of the big differences between the actual data and how we’ve heard it talked about a lot,” Cochrane says, “is that immigrants are much more similar to non-immigrant Canadians than they are different.”

Many Canadian-born voters abandoned the Liberals for the Conservatives in the past three elections, and voters born abroad did, too. “Immigrants did it slightly more, but not incredibly more,” says Cochrane. In fact, he says the clearest difference between native-born and foreign-born voters is the strong tendency in Quebec for immigrants to not support the separatist Bloc Québécois. Among various ethnic groups, however, he says different partisan leanings are clear. For instance, Cochrane points to stronger support among immigrants from India and Pakistan for the Liberals; among immigrants from East Asia for the Conservatives; and among immigrants from Africa for the NDP.

Among the most unpredictable factors in the current campaign is Harper’s emphasis on his government’s proposal to ban the wearing of face veils, particularly the niqab worn by a small minority of Muslim women, during the swearing of the citizenship oath by new Canadians. According to Ipsos Reid online survey data collected after the 2011 election, Muslim immigrants overwhelmingly voted Liberal or NDP. So the bigger question in this campaign is how immigrants from other religious backgrounds respond to this controversial Conservative measure directed primarily at a few Muslims.

No matter what the result on Oct. 19, strategists from all parties will pore over the results of exit polls to figure out how immigrants voted, especially in that dense band of seats around Toronto. Cochrane predicts they’ll see national patterns repeated, with surprisingly slight variations. “On virtually every indicator, the level of immigrant integration in Canada is the envy of the world,” he says. “You think of things like rates of intermarriage, rates of acquiring citizenship, political participation—these things we’re doing incredibly well.” For all the attention to newcomers in this election, the most intriguing outcome might be if they end up voting a lot like, well, Canadians.