With less than a week to go before Monday's byelections, the Conservatives have launched the latest assault: a mailout to voters in Manitoba's Brandon Souris riding that baldly states the Liberal leader "does not have the judgment to be prime minister."
The pamphlet comes complete with a series of controversial Trudeau quotations, some dating back almost 15 years and at least one taken out of context.
It pillories the Liberal leader for wanting to legalize marijuana, "making it easier (for) kids to get," and for saying he'd repeal mandatory minimum sentences, "meaning those convicted on multiple counts of sexual crimes would serve shorter jail terms."
It also paints the Liberal candidate in Brandon, Rolf Dinsdale, as a tourist who only moved back to the riding in the summer and once played in a crudely named punk band that performed songs with raunchy lyrics.
Polls have suggested Dinsdale, whose father was Brandon's Progressive Conservative MP for more than 30 years, could snatch the riding away from the Conservatives.
The other Manitoba riding in play is Provencher, a longtime Tory bastion that is widely expected to remain within the governing party's fold and, hence, has seen relatively little controversy.
But Trudeau and his candidates have also come under fierce attack from the NDP in Toronto Centre and the Montreal riding of Bourassa, two Liberal strongholds the New Democrats are making an all-out effort to steal.
Trudeau is accusing NDP Leader Tom Mulcair of taking a page out of the Conservative playbook.
"Mr. Mulcair has obviously decided that the Conservative approach that Mr. (Prime Minister Stephen) Harper has effectively built over the past few years is indeed the best way to function," he said Tuesday.
And he's getting support for that charge from the Green party, whose Bourassa candidate last week issued a news release denouncing the NDP for "negative campaigning."
Green Leader Elizabeth May said the success of the Conservatives' negative approach to politics has persuaded the NDP to adopt the same approach, which she fears is slowly becoming "the new normal" in Canadian politics.
"Stephen Harper has introduced into Canadian politics the nastiest level of hyper-partisanship, the use of attack ads that are focused on the personality of other leaders," May said in an interview.
Ultimately, she said, negative campaigning will only "reinforce the notion that this is all a dreadful, hyper-partisan exercise in spin, which has the effect of driving down voter turnout."
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"In fact, hundreds of NDP signs have been removed but we actually have the film of the Liberals taking down one of our signs. So, the only dirty tactic that I know about in that byelection is from the Liberal Party of Canada," Mulcair said.
Trudeau countered that the sign was taken down only after the NDP campaign ignored phone calls requesting that it be removed. The fact that the NDP set up a camera to "catch one of our enthusiastic volunteers" removing the poster "indicates exactly the kind of approach that they're choosing to take in politics, which is to play edgy, mean, nasty games to do anything to try and win," he said.
The poster in question targets Dubourg for taking a $100,000 severance payment when he quit the Quebec legislature, less than a year after winning re-election, to run federally. It depicts him as a charter member of "Club Privilege Liberal," an opportunist who is running "to satisfy his personal ambitions."
A "club privilege" website set up by the NDP makes similar arguments and also goes after Trudeau for being "invisible" on the Senate expenses scandal, suggesting that's because Liberal senators are also implicated.
In Toronto Centre, the NDP campaign echoes the successful Tory attacks on Trudeau's predecessor, former Harvard professor Michael Ignatieff, as an opportunist who was "just visiting" Canada and who "didn't come back for you."
New Democrats have zeroed in on the fact that Liberal candidate Chrystia Freeland, a journalist and author who left an executive position with Thompson Reuters in New York to enter the political fray, has not lived in Canada for 10 years.
NDP candidate Linda McQuaig, who is also a prominent journalist and author, has adopted "from Toronto, for Toronto" as her theme. Young New Democrats have posted online a picture of a big, outdated mobile phone — the way cell phones looked when Freeland was last living in Canada.
New Democrats have also gleefully dredged up Freeland columns in which she professed admiration for former British prime minister Margaret Thatcher and former Republican vice-presidential candidate Sarah Palin.
McQuaig "totally rejects" charges that the tone of the campaign has been nasty and makes no apologies for drawing attention to the fact that Freeland only moved back to Toronto a few months ago.
"That's a true fact and I do think that's something that voters in Toronto Centre have a right to know," McQuaig said, noting that Freeland calls the riding her "home" in her campaign literature without revealing "it's only been her home for four weeks."
Similarly, NDP national director Nathan Rotman argued there's nothing wrong with campaign messages that encourage voters to "compare and contrast" candidates or which criticize an opponent's record or policy stances. Such approaches aren't the same as personal attacks, he said.
In the dying days of the campaign, Freeland's team has finally begun to fight back, dredging up its own quotes and clips that, among other things, suggest McQuaig's pro-Palestinian stance is at odds with Mulcair's staunch support of Israel.
However, Trudeau insisted Tuesday that he won't be drawn into negative campaigning that's "focused on slander and attack." Indeed, he said the attacks against the Liberals from opposing parties are proof that his more positive approach "is getting a tremendous amount of traction" in the byelections.