Ed Broadbent is chair of the Broadbent Institute.

As our American cousins gathered on their Thanksgiving weekend to wrestle with the reality of a Donald Trump presidency, Canadians should already have absorbed an important lesson from this month's U.S. election.

It is this: A change to proportional representation (PR) as the means of electing our federal government would be the firewall against a northern Trump riding a right-wing populist wave to victory.

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Consider that under our current first-past-the-post system, successive Harper and Trudeau governments have rolled to majorities with the support of fewer than four in 10 voters.

Consider that a leading Conservative leadership candidate, Kellie Leitch, has hailed the Trump victory as an exciting message that must be delivered here, as she continues to peddle her "Canadian values" mantra to the party faithful.

And consider that Van Jones, a leading CNN analyst and former Barack Obama adviser, warned at a Broadbent Institute gala this past week that a Trump-like victory could happen here. Mr. Jones urged progressives to push back with an "army of love."

That army should be carrying PR as its weapon of choice.

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Three weeks after Mr. Trump gained enough electoral college votes to be declared president-elect, final ballots are still being counted and Hillary Clinton has more than two million more votes than her opponent.

This is not an anomaly. It has happened before in recent history. George W. Bush became president in 2000 even though Al Gore won the popular vote. Clearly, based on the popular vote, with a system of PR, Hillary Clinton would now be the president-elect.

We'll leave our American friends to sort out their electoral-college concerns, but the question for Canadians is whether a PR system could block a Trump here.

The answer is yes, because PR rewards voters with a fair outcome. A party that wins 40 per cent of the vote will win only about 40 per cent of the seats, not a majority. A party winning 30 per cent will be rewarded with 30 per cent of the seats, and so on.

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Voting levels should rise because it would end the prevailing sense among many Canadians – a New Democrat or Liberal in rural Alberta or a Conservative in downtown Toronto or a Green basically anywhere outside of Elizabeth May's riding – that their votes are being wasted.

It would end the egregious results we have seen before. For instance, the 1997 election in which the Bloc Québécois obtained twice as many seats as the NDP despite winning fewer votes – none of them, of course, outside Quebec.

In the same vote, the former Reform and Progressive Conservatives won a like number of ballots, but Reformers garnered three times the seats.

In 1979, Pierre Trudeau outpolled Joe Clark, but Mr. Clark formed a minority government. In 1957, John Diefenbaker formed a government after winning fewer votes than Louis St. Laurent.

We often hear that PR would give seats to extremist parties. That's very rare because countries with such a system have established a threshold each must cross to win seats.

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A parliamentary committee is meeting to try to forge an alternative to the first-past-the-post system and must deliver its report by Thursday. But Democratic Institutions Minister Maryam Monsef is doing all she can to fuel suspicions that the Trudeau government will renege on its promise of a new electoral system in the next election.

Of those who testified before the committee or attended town hall meetings across the country, the vast majority of experts and average Canadians (80 per cent, in fact) back PR.

Yet Ms. Monsef continues to cling to the fable that she has heard no consensus. This is incorrect and unacceptable.

If Prime Minister Justin Trudeau is serious about having voters vote their values and have that reflected in the composition of the House of Commons – and delivering on a key and oft-repeated campaign promise – the most important thing he can do is support proportional representation.

Or we could wait until an unfair system allows a Trump-style government to gain a toehold in our backyard.