With both opposition parties leaderless and with millions still mourning the loss of Jack Layton, voices within both the NDP and the Liberals have again raised the question of whether the two parties should merge.
But that merger cannot and will not happen soon, if ever. The laws of political nature won't allow it.
Ignoring those laws, NDP MP Pat Martin said Tuesday that if no candidate runs for his party's leadership on a merger platform, he'll do it himself, while Liberal MP Denis Coderre is urging a "serious discussion" of a union.
Such talk is understandable. We've never been in a situation where neither opposition party in the House of Commons has a permanent leader. With no one in either party having the authority to squelch such talk, merger speculation fills the leadership vacuum.
Reporters peppered interim leader Bob Rae with questions about a possible merger during the Liberal caucus retreat Tuesday.
"The debate will happen," he acknowledged. But "is it a debate about something real? My answer is no."
Mr. Rae is right. When progressive politicians look at the success of conservatives united under Stephen Harper's Conservative Party banner and ask: Why not us? they ignore the self-evident answer: You're not them.
"Dogs of different breeds can make a family," says John Duffy. But the current consultant and former Liberal strategist points out that the Liberal and the NDP "are different species."
For a social democratic party of protest to merge with a traditionally centrist party of power, either or both will have to rearrange their political DNA.
Beyond that, pro-merger progressives ignore history.
It took 10 years, three elections, six leaders, several name changes and many failed attempts before reasonable voices in both the Canadian Alliance and Progressive Conservatives acknowledged that neither party would ever form government on its own. Merger can only happen when both sides can see their future clearly, and that future is bleak.
But the future is not that bleak for the Conservatives' opponents, at least not yet. The NDP honestly and reasonably believes that it has a shot at winning the next election. The Liberals honestly and reasonably believe that with a new leader, a new party structure and a clear set of policies, they will once again become the obvious governing alternative.
Until both parties no longer have reason to hope, neither has reason to merge.
Beyond that, the two parties will be fighting each other across the country in provincial elections this fall and into next year. Just ask the B.C. Liberals and NDP what they think of the idea of a merger.
"In politics, timing is everything," observes Robin Sears, the former national director of the NDP who is today a consultant. "And this ain't the right time."
That does not mean, he adds, that people of good will in both parties can't talk to each other about possibly co-operating in the runup to the 2015 election. But now is not the time for those talks. And the time, says Mr. Sears, is probably "later rather than sooner."
The current lines of force in Canadian politics will shift, because they always do. One day we will be writing about the efforts of a Conservative leader to hold the party together in the face of impending defeat, as a new governing alternative surges in confidence and popularity.
But this is not that day. And attempts at forcibly merging parties that aren't ready for it won't bring that day any closer. As Bob Rae said, it's not that the door is closed. There isn't a door.