Prime Minister Paul Martin will bring down a Speech from the Throne today, that he hopes will set the national agenda for the coming federal election. Governor-General Adrienne Clarkson will extol the vision of a new Canada in a new century, committed to economic innovation, urban renewal, a New Deal for First Nations, and a confident and militarily robust role in world affairs.

There is another item on that agenda, one Mr. Martin has been trying to ignore. Five provinces ��� British Columbia, Ontario, Quebec, New Brunswick and Prince Edward Island ��� are at various stages in their evolution toward a new electoral system based on some form of proportional representation. And the Law Commission of Canada has revealed that it will recommend the same for the House of Commons.

The question is whether Mr. Martin, who wants to make Parliament more accountable to its own members and to the public, is prepared to embrace electoral reform, or whether he will shunt it aside.

Moving our provincial and federal governments away from the current first-past-the-post method of selecting legislators, and toward one of the several proportional systems already in use in most developed countries, would profoundly reshape Canadian politics.

Journalistic exaggeration? Consider what would happen if this spring's election were fought under PR rules, with the results reflecting the most recent Ipsos-Reid poll.

The Liberals would have 148 of the 308 seats in the House of Commons ��� impressive, but not good enough to form a government, which means Prime Minister Paul Martin would need to seek a working relationship with another party.

Assuming he refused to talk to the Bloc Qu��b��cois (which, under PR, would be reduced to 31 seats in the House), Mr. Martin would have three choices.

If he wanted to govern from the right, the Prime Minister might approach the Conservatives, who would have 59 seats. Would they agree to join a government of national unity?

Mr. Martin would first have to commit to substantial tax cuts and aggressive debt reduction, sacrificing his cherished programs for urban renewal and help for natives.

If that was too much for him to take, Mr. Martin might approach Jack Layton, who would be leading the NDP's first-ever 49-seat caucus.

But what price NDP support? At the least, an end to Canadian participation in the national missile-defence system, part of a general chilling of Canada-U.S. relations that would accompany a Liberal-NDP coalition government.

Or maybe Mr. Martin would want to talk to the Green Party, which would have 12 seats in the House.

Would they give their support in exchange for strong commitments to adhere to the Kyoto Protocol on global warming? Perhaps that would be enough for a shaky Liberal-Green coalition.

Things would certainly be interesting. They could also be unstable. With each succeeding election, more political parties might appear.

The Conservatives could split again into their Prairie-populist and Eastern-establishment wings.

Support could bleed from the NDP to the Greens.

Even the Liberals could be riven by factions, with Sheila Copps Liberals forming a separate caucus from Martin Liberals.

Those who favour efficient government would despair at all the compromises involved in brokering a working coalition. But then, such brokerage already happens within political parties, much of it hidden from public scrutiny.

There is a bigger issue. Since Confederation, Canada has grappled with geographic, linguistic and cultural divisions. Will a move to PR foster factional parties that cater to and exploit local grievances? Or are we now mature and confident enough as a nation to elect stable coalitions that govern in the national interest? Are we, in other words, the Canada that Mr. Martin claims we are?

The Prime Minister, through Justice Minister Irwin Cotler, will give his initial response to the Law Commission report after it is presented to the House in March. But nothing will be, or should be, attempted before the spring federal election.

The real choice for Mr. Martin will come after the election. Assuming he wins it, he can then either let the issue languish in some committee, waiting to see how things play out in the provinces, or he can put it on a front burner, asking for public consultation and a report that could produce electoral reform in time for the 2008 election.

No one should want to rush into this: We don't know whether most Canadians even understand what a move to PR would entail, let alone whether they would approve such a change.

But for better or worse, electoral reform is now on the national agenda. The Law Commission has put it there.