The great political migration of Canada's Jewish community from the Liberals to the Conservatives is almost reflexively attributed to Prime Minister Stephen Harper's emphatic support for Israel: If Mr. Harper champions Israel, the Jewish community will champion him.

The motivation is depicted as political strategy or profound, emotional affinity. Either way, it is the Conservatives who are pushing hard. Whether slapping down Palestine's symbolic bid for UN statehood, kicking out diplomats from Iran or casting huge doubts on the rogue country's nuclear deal with Western powers, the Conservative government takes a "principled stance." Or as others would have it, dirty wedge politics. No matter how you define it, Ipsos-Reid estimated that 52 per cent of Jews voted for the Tories in the last election, a historic exodus of political heft that has left the Liberal Party lacking.

A capstone of this shift will come on Sunday, when the Jewish National Fund pays tribute to the Prime Minister at its annual Negev Dinner, celebrating him as Israel's best friend. But leading up to the event, Jewish leaders indicate it is not simply pandering that won him the vote. The community was already halfway there.

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Despite their long history with the Liberal Party, like many other other minorities, Jews had felt taken for granted in the early 2000s. Demoralized by the fizzling of the Oslo Accords, frightened by the rise of vitriol from a possibly nuclear Iran, and troubled by anti-Israel activity on Canadian campuses, many Jews felt profound existential angst. Some fretted that the Liberals were not rising to their defence.

At the same time, the Orthodox community, which typically votes Conservative, was – and still is – experiencing a population boom. "A portion of Jews have become more conservative, and as a result, have become more concerned with Israel's security," said Morton Weinfeld, a sociology professor at McGill University. "But there are also other factors that come with above-average incomes and better occupations."

Canadian Jews are generally liberal in their social policies – but they are especially ardent Zionists. Almost three quarters of Toronto and Montreal Jews have visited Israel. Less than half that percentage of U.S. Jews have done the same. A 2006 analysis found that 42 per cent of Canadian Jews identify themselves as Zionists, compared with 25 per cent of their U.S. counterparts.

For more moderate or secular voters, issues such as economic stewardship and community funding are also part of the equation. In that case, many secular Jews may not see a huge difference between the two party platforms. "There is a blurring of economic and social values that makes it easier for voters to swing either way," said Jack Jedwab, executive vice-president of the Association for Canadian Studies. While it may be a crowded centre, Mr. Harper's views on Israel help tip the balance.

Senator Linda Frum, who is co-chairing the Negev Dinner, recalled meeting Mr. Harper for the first time in 2001, when she was disaffected with the Liberals. Even then, she said, the future prime minister demonstrated a bond with her community that went back to childhood. "His father was very sensitive to the anti-Semitism of that time and spoke of the injustice of it to him when he was a boy," she said. "And now it disturbs him when he sees his peers on the world stage caving to international pressures or domestic concerns."

It took several decades for Jews to warm to the Tories. While many saw a close ally in Progressive Conservative prime minister Brian Mulroney, there was wider distrust about his caucus.

The sentiment continued with the right-wing Canadian Alliance party and an anti-Israel element in its caucus. But the more mainstream Conservative Party that emerged became a draw. Its pre-eminent voices – Stockwell Day and John Baird – had been to Israel and were supporters. There was solidarity on the benches.

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Ms. Frum remembered her first caucus meeting in 2009, a closed-door discussion in which the Prime Minister spoke sharply about a communication he had with Iran about its nuclear program. "I was stunned," she recalled. "I knew he was supportive, but I saw these MPs from Saskatchewan and Nova Scotia and Alberta standing and applauding. I felt overcome with tears. I didn't understand how deeply this ran in the party."

At the same time, Liberal parties across the map have been trying to reconcile social justice and their support for Israel. Jews and other minorities have gravitated toward left-of centre politics since the beginning of the last century because of their experience with persecution. But after Israel's war in Lebanon in 1982, the country lost its underdog image and faced increasing criticism from the left. For many Jews, Liberal parties became uncomfortable tents.

In the 1990s, many Jews felt the party talked out of two sides of its mouth. Prime minister Jean Chrétien delivered a free-trade agreement with Israel, but his government's voting pattern at the United Nations was infuriating. His successor, Paul Martin, was considered a big supporter, but lost power. In 2006, leader-to-be Michael Ignatieff talked about war crimes for Israel's attack on Lebanon, a remark for which he later apologized. And while Mr. Ignatieff then rushed to centre, the migration to the Tories had already begun.

"It's no secret we made some errors with some of the different groups who supported us," federal Liberal Party president Mike Crawley said. "One of them was the Jewish community. We certainly drifted, but under Bob [Rae] and Justin Trudeau, we've tried to engage more."

Mr. Crawley said the party is reaching more deeply into the community for new leadership and has created an aggressive Twitter campaign to explain its policies on the Jewish community. He also says that "there isn't much daylight" between the Liberals and Conservatives on Israel.

Only this week, the Liberals issued a skeptical statement on the Iran nuclear deal, albeit more measured than that of the Conservatives. Some Jewish leaders said this is a shrewd tactic, forcing Tories to become even more vocal about their support. Or shrill, some might say.

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One concrete advantage the Liberals have is that, unlike Mr. Harper, Mr. Trudeau has been to Israel.

It's a start.

Follow me on Twitter: @Craigoffman