As we enter the post-parliament stage of what is shaping up to be a 180-day federal election campaign an unlikely issue has emerged – proportional representation. Weirder yet, it’s the Liberals who are pushing the idea.

The notion that we need to replace our first-past-the-post (FPTP) electoral system with something better has long been included in NDP and Green Party election platforms. In the past, both parties would certainly have benefitted from a regime that apportioned seats in the House of Commons more in accordance with a party’s share of the vote. In 2008, for example, if seat share had approximated vote share, there would have been 55 New Democrats elected instead of 36. For the Greens, PR would have had an even more dramatic effect. Instead of being shut out of the House of Commons in 2008, they could have elected up to 20 members.

The picture changed somewhat in 2011. Thanks to their breakthrough in Quebec (courtesy of the partial collapse of the Bloc Quebecois), the NDP actually benefitted slightly from FPTP, electing 103 MPs instead of the 95 that would have come their way had seat share aligned strictly with vote share. For the Greens, 2011 was a mixed bag. Good old FPTP delivered their first-ever seat when Elizabeth May won the B.C. riding of Saanich-Gulf Islands with 46% of the vote. But to discourage fringe parties, most PR systems have a minimum threshold (usually five per cent) that must be achieved before parties are allocated seats on a proportional basis. The Greens managed only 3.9% in  of total votes in 2011, down from 6.8% in 2008. Had PR with a five per cent threshold been in existence in 2011 the Greens would have achieved exactly the same result as they did under the current system- one seat.

But the Liberals were the main victims of FPTP in 2011,  winning only 34 seats instead of 60 odd they may have picked up with PR.  And there is nothing quite like a disastrous election result to get the Liberals talking about changing the FPTP system that served them so well for most of the 20th Century. In 2004, after the election reduced it to a minority, and under pressure from the NDP, the Paul Martin government’s throne speech promised to “examine the need and options for reform of our democratic institutions, including electoral reform.” Nothing much came from that undertaking, but after the 2011 Liberal debacle, replacing proportional representation moved up the priority list. Party members at a policy convention in 2012 endorsed replacing FPTP, giving Justin Trudeau a handy plank in the platform of democratic reforms he unveiled last week in a desperate response to his party’s drop to third place in the latest round of public opinion polls.

Beyond the politics of it, what gives significance to Trudeau’s announcement is that three parties now endorse some form of proportional representation. Should one of them win the next election, they will be hard pressed not to follow through with reform.(The Nova Scotia NDP had PR in its policy book for years but never featured it in recent election platforms. They therefore had no mandate to proceed with it during their time in office, an omission that, given the results of the 2013 election – only 13% of seats with 27% of the vote – some may now regret).

Changing FPTP will not be easy. The first hurdle will be finding a model that even its proponents agree upon. The NDP favour a mixed member system under which a certain percentage of MPs are chosen through FPTP at the riding level while another batch are elected off  lists based on each party’s share of the overall vote. The Liberals prefer a system in which choices are ranked. Under that approach, if the top candidate fails to receive a majority of votes, the second choice of lowest ranked candidates are counted until one candidate has more than 50% of the votes cast. As for the Greens, they may balk at any attempt to impose a threshold.

Whatever model is chosen will have to be generally acceptable to the Canadian public. Within the last decade three provinces – British Columbia, Ontario and Prince Edward Island – have held referenda on proportional representation and in all cases the proposals were defeated by fairly wide margins. Perhaps that’s why Trudeau prefers to avoid a referendum, instead leaving it to a parliamentary committee to come up with a plan within 18 months. The NDP was more coy on the referendum issue, with spokesman Peter Julian telling the Globe and Mail that the method of consultation will be discussed “once we get the mandate.”

By not jumping to a referendum, the opposition parties left the door open to another strange event – a stirring defence of democracy by Conservative minister Pierre Poilieve, that hyper-partisan architect of the voter suppression and associated schemes cooked up for inclusion in the misnamed Fair Elections Act. “Every time Canadians have voted on this, they chose to keep the current system,” he told the Globe. “We will continue (sic) to respect the democratic will of Canadians.”

So the gauntlet has been thrown down. But having the Conservatives emerge as the defenders of FPTP may turn out to be a godsend for supporters of  proportional representation. Even casual observers will realize that the Conservatives are the prime beneficiaries of  the electoral status quo – 54% of the seats in the House of Commons with only 40% of the vote in 2011. So naturally the Conservatives want to keep it. In looking after their own self interest, they may be no worse than the others.

But looking a little deeper reveals how FPTP, combined with divisions on the centre and left, have led directly to the kind of politics we have been subjected to over the last four years. With their opponents divided and FPTP prevailing, the Conservatives have been able to govern for their core supporters, ignoring the concerns and values of the majority of Canadians. To name just the most egregious examples, foreign affairs, the environment, aboriginal policy, corrections, privacy, culture, economic and regional equality, taxation policy, the public service and the military have all been politicized through neglect, distortion or direct attack, all in the name of keeping the Conservative base onside.

The trick for proponents of electoral reform will be to avoid getting involved in a detailed discussion of the nuts and bolts of PR. That approach helped to scuttle previous campaigns. Instead, they need to focus on the evils of the status quo, as exemplified by the Harper Conservatives. Even if those Conservatives are defeated in the next election, (if they are not, talk of PR is moot) the continuation of FPTP leaves open the possibility that the kind of toxic politics practiced by the Harper Conservatives will make a comeback. PR, even with a few imperfections, has to be better than that.