New Democrats say they'd two-step with the federal Liberals if it meant ousting Prime Minister Stephen Harper's Conservatives, but their prospective dance partner isn't hearing the music.
NDP Leader Tom Mulcair said Thursday that his party has always seen the defeat of the Conservatives as a priority.
"We know that they've done a lot of harm, and we want to start repairing the damage that (Harper's) done," Mulcair said from Amherstburg, Ont., where he stopped as part of an eight-day tour.
"We've always worked with others in the past, but every time I've raised this prospect with Justin Trudeau, he's slammed the door on it."
The Liberal leader did that again on Thursday when asked in Winnipeg about the possibility of a formal coalition with the New Democrats.
"Although of course we are open to working with all parties in the House to pass good legislation and to ensure that Canadians' interests are served, there will be no formal coalition with the NDP," Trudeau said.
"There are fundamental differences of opinion on very important elements of policy — whether it be Canadian unity or the Canadian economy and the need for growth — that we disagree with the NDP on."
Nathan Cullen, NDP MP for Skeena-Bulkley Valley in British Columbia, raised the issue again in an interview Wednesday. He said winning a majority in a federal election expected this fall remains his party's goal, but ultimately the No. 1 priority is toppling the Tories.
"The Liberal voters that I know are as fed up with Stephen Harper as anybody," Cullen said.
"Justin Trudeau will do himself a great deal of damage with progressive voters if he wants to contemplate more years of this Harper government."
The last time the idea of a coalition government was seriously floated was in 2008, when the NDP, Liberals and Bloc Quebecois came together to try to force the government out of office.
Their efforts were thwarted when the Governor General, at the prime minister's request, prorogued Parliament, effectively putting it on pause until the new year, by which time there had been a change in Liberal leadership.
The new leader, Michael Ignatieff, ultimately backed out by grudgingly supporting the Conservative budget. That saved Harper from losing a confidence vote and having to call an election.
That deal only would have been possible by including the separatist Bloc Quebecois. That was unpalatable to the Liberals.
"The NDP said we were willing to make (Liberal) Stephane Dion the prime minister. We thought it was important to replace Mr. Harper's Conservatives," Mulcair said.
"The Liberals signed a deal. They walked away from it. And, seven years later, we've still got Stephen Harper's Conservatives."
A few years ago, when Liberal fortunes were plummeting, it was Mulcair who categorically ruled out a coalition. He has since suggested those comments were intended to indicate only that he wouldn't agree to any electoral co-operation with the Liberals during a campaign.
Coalitions are relatively common in other parliamentary democracies, such as Germany, but they occur far less frequently in Canada, where the first-past-the-post electoral system favours the formation of majority governments.
Voters are expected to go to the polls on Oct. 19, as per Canada's fixed-election-date law. However, nothing prevents the prime minister from asking the Governor General to dissolve Parliament and send Canadians to the polls earlier.