Political leaders in Canada are experiencing a surge in public support as they focus their efforts on the non-political work of fighting the COVID-19 pandemic.

But they can't count on that praise lasting forever. History shows that leaders who are popular in a crisis still risk being kicked out of office once things return to normal.

After a bruising election last year, Prime Minister Justin Trudeau now finds himself back in voters' good graces thanks to his handling of the pandemic. He isn't the only one.

Polls suggest that big majorities of voters in every province approve of their premiers' management of the crisis. Quebec's François Legault leads the group with between 88 and 95 per cent approval on the issue, according to two recent polls by Léger and Research Co. , but his colleagues around the premiers' table aren't too far behind.

The measures put in place by Trudeau's federal government have the approval of 76 per cent of Canadians, according to Léger — an increase of 11 percentage points since the end of March.

That has boosted support for Trudeau's party to 39 per cent of decided voters, giving the Liberals an 11-point lead over the Conservatives in Léger's polling. That margin has widened by nine points since last month.

According to Nanos Research , Trudeau is the choice for prime minister preferred by 38 per cent of Canadians; just 17 per cent picked Conservative Leader Andrew Scheer. What was a 13-point gap between the two leaders in early March — before the novel coronavirus outbreak was starting to shut down the country — is now 21 points.

An election in the midst of the pandemic is hard to imagine, although Elections Canada is thinking about how one might be held if it becomes necessary. The experience of South Korea , however, shows what a crisis and a favourable electoral calendar can do to a party's fortunes.

South Korea has had fewer cases and deaths than Canada and its government saw a bump in the polls ahead of this past week's parliamentary elections, in part due to its handling of the virus. The result was a landslide victory for the governing party — the biggest for any party since democracy was restored in South Korea in 1987.

But timing is everything in politics — and things don't always work out that well for people in power once a crisis is in the rearview mirror.

The fall from the heights can be steep ...

There are many historical examples of political leaders securing re-election thanks to a wave of support coming out of a victorious war or successfully-handled crisis. There are also some notable exceptions.

On the very day in 1940 when German tanks started rolling into the Netherlands, Belgium and France, Winston Churchill became the British prime minister and head of a war cabinet featuring members from opposing parties.

He led the United Kingdom through the Second World War, inspiring its citizens to resist even when the British Empire was alone in the fight against Nazi Germany. But victory over Adolf Hitler in 1945 did not secure victory for Churchill's Conservatives at the polls — he was decisively defeated and replaced by Clement Attlee's Labour Party in that year's election. (Churchill did return to power for one more term in 1951.)

After leading the United Kingdom through the Second World War, British prime minister Winston Churchill was defeated in the 1945 general election. (Eddie Worth / Associated Press)

After ending American involvement in Vietnam, U.S. president Richard Nixon was at the height of his popularity with an average approval rating of 69 per cent in March 1973. Little more than a year later, when he was facing likely impeachment over Watergate, Nixon resigned with an approval rating well under 30 per cent.

Coming off the successful completion of the Gulf War, and with U.S. forces starting to come home from Iraq, U.S. president George H.W. Bush had an average approval rating of 86 per cent in March 1991.

A slumping economy, however, helped push Bush's approval rating below 50 per cent before the end of the year. It was under 40 per cent by the time of the 1992 presidential election, which Bush lost to Bill Clinton, denying him a second term.

... but it's not always fatal

Falling popularity did not cost his son, George W. Bush, a second term in 2004. Bush had only a middling approval rating in the months following his contested 2000 victory. But after the September 11th terrorist attacks, his rating soared to 88 per cent — among the highest ratings for any modern U.S. president.

That sympathy slowly faded and dropped below 50 per cent by early 2004. But his rating did not sink much further than that and he was able to win re-election in November of that year. By the end of his second term, though, Bush's approval rating was as low as Nixon's before his resignation.

During the 1998 ice storm, Quebec Premier Lucien Bouchard was praised for his management of an emergency that left a significant chunk of the province (as well as parts of Ontario and New Brunswick) without electricity for days and even weeks.

In the months after the ice storm, polling by Léger put Bouchard's Parti Québécois at 49 per cent support, up eight points from where it stood before the crisis and comfortably ahead of the opposition Liberals.

But it wasn't long before the PQ was trailing the Liberals in the polls again. In the provincial election in November 1998, Bouchard was able to win another majority government — but with less of the popular vote than the Liberals won. He didn't complete his mandate, resigning in early 2001.

Legault knows this example very well — he joined Bouchard's cabinet a few months after the ice storm . Trudeau also can draw from his own personal history for an example of the ephemeral nature of a crisis-induced surge in popularity.

Pierre Trudeau's support surged shortly after the October Crisis of 1970, but two years later he nearly lost the 1972 federal election. (Peter Bregg/Canadian Press)

After the October Crisis of 1970 — when the Front de libération du Québec kidnapped two officials, murdering one of them, and prime minister Pierre Trudeau invoked the War Measures Act (famously telling one reporter to "just watch me" when asked how far he would go) — support for the Liberals soared to 59 per cent in a December 1970 Gallup survey.

That put the Liberals 37 points ahead of the Progressive Conservatives — an increase of 23 points over their margin of victory in the 1968 election. But by May 1971, support for the party was already below 1968 levels and by early 1972 the party trailed Robert Stanfield's PCs, according to Gallup.

In the October 1972 election, Trudeau lost his majority and very nearly his government. He eked out a plurality by a margin of two seats over the PCs and stayed in office with the support of the New Democrats. Though he was able to regain a majority government in the 1974 election, he had only narrowly avoided becoming a one-term prime minister.

Had that occurred, it is likely that his son wouldn't be leading the country through the current COVID-19 crisis. So far, Canadians think Justin Trudeau and his fellow heads of government are doing a good job handling a bad situation.

But that doesn't necessarily mean Canadians will reward them when it's all over.