The dynamics have changed. Where once Justin Trudeau shrugged off the NDP, insisting his opponent was Stephen Harper, the Liberal Leader has made the telltale decision to switch targets.
Now, the Liberals are campaigning like the third-place party, attacking Thomas Mulcair and the New Democrats rather than keeping their guns trained solely on Mr. Harper and the Conservatives.
That is driven by the reversal of fortunes for the two opposition parties in which the NDP has taken the lead in many polls, with the Liberals in third. But many Liberals are also feeling that the fall election is shaping up as a referendum on whether Mr. Harper and the Conservatives stay or go – and that those in the latter camp will coalesce behind whichever party seems mostly likely to displace them.
And if that is the case, they fear, Mr. Trudeau cannot afford to go into the official campaign too far behind Mr. Mulcair. So they are trying to knock him back in the weeks before the writ is dropped.
On Monday, while Mr. Mulcair was launching a tour of southern Ontario ridings that have mostly been unthinkable long-shots for New Democrats, the Liberals sent out Adam Vaughan, a left-leaning downtown Toronto MP, to attack the NDP for policies that he said would help the wealthy, not the middle-class.
The party put out a press release in which Mr. Vaughan cited a collage of complaints, starting with the fact that the NDP opposes Mr. Trudeau's proposal for middle-class tax breaks aimed at low- and middle-income families, and that it opposes the Liberals' plan to hike taxes for more affluent Canadians. But it was rounded out with charges that Mr. Mulcair would re-open the Constitution (to try to abolish the Senate) and make it easier for Quebec to separate (by setting the threshold at 50 per cent plus one.)
Many Liberal candidates think it is about time for such a move. They have been watching the party's poll numbers darken, along with some of their own election prospects. It is time "to raise questions" about Mr. Mulcair and the NDP, one said, such as whether their policies are really progressive, and what the party leader thinks of free trade. "Who would be their finance minister?" another candidate asked rhetorically. Expect Mr. Trudeau to be "increasingly feisty" in making these points.
Liberal ranks have experienced a loss of confidence. Some have also lost faith in the people around Mr. Trudeau, saying they should have done more to consolidate their gains when he was enjoying a wave of popularity, and questioning whether they have a clear plan to reverse the decline. Others see the drop in polls as the inevitable result of the non-stop barrage of Conservative attack ads that say Mr. Trudeau is not ready – and they think the real test will come when the campaign really heats up.
But many Liberals have another reason for wanting to hit the NDP now: the idea that Liberal and NDP voters are part of a pool that wants change and will turn to whomever they think can provide it.
Some Liberal candidates said they feel a palpable desire for change – not necessarily that Mr. Harper's supporters have turned against him, but that those who were not really his supporters are more fed up. But that sentiment is more about Mr. Harper than the alternatives.
Of course, the goal of the Conservatives is to make those alternatives seem less palatable to voters.
For now, they are still mostly focused on Mr. Trudeau's Liberals, who, after all, were historically the alternative, and are more centrist. But they have a plan: If that succeeds, they will attack the NDP as risky, too.
It is the Liberals who cannot afford to wait. Mr. Trudeau now leads a nervous party. It fears what the NDP long feared: being out of the race before a campaign officially begins. The Liberals have to try to cut Mr. Mulcair's momentum back. And in doing so, they are underlining how much things have changed.