Lavigne - the brilliant Jack Layton loyalist who helped pilot the New Democratic Party to its historic gains in the election of one year ago - seemed uncertain, however briefly, about what his answer should be.

In an exchange with Tim Powers - the much-liked Conservative Party pundit - Lavigne had been asked about when Stephen Harper's war room intended to start attacking newly minted NDP Leader Thomas Mulcair.

Lavigne eyed Powers warily. The two political strategists were on a stage at the Ottawa Congress Centre for the annual gathering of Canadian realtors. Finally, Lavigne allowed that he did not know, exactly, when the ruthless Conservative attack machine would strike. "But it's coming," Lavigne said. "It's coming."

Indeed it is. But when? And, more significantly, why hasn't it happened already?

The questions aren't irrelevant. Shortly after Stephane Dion won the Liberal Party leadership in 2006, the Conservative Party's war room got to work. They didn't mince words.

"Stephane Dion is not a leader," the Conservatives declared, in ads that were seen by Canadians many, many times.

In the election that came afterwards, the Liberals had a new leader, but the Conservative strategy was largely the same. Michael Ignatieff, the multi-million-dollar advertising barrage declared, was "just visiting." It helped to drive the once-mighty Grits to their worst showing in history.

A year or so later, the Liberals had a new leader, and the Conservatives again wasted no time.

"Bob Rae," the new ads intoned, after reciting the sad tale of his Rae's tenure as NDP premier of Ontario. "If he couldn't run a province, why does he think he could run Canada?"

Dion, Ignatieff, Rae: The words changed, but the approach did not. Before the Liberal leaders could define themselves, the Cons sought to define them first. In every case, the attack didn't concern itself with a particular policy. It was always about character. Dion: A weakling. Ignatieff: An alien. Rae: An incompetent.

So where, in all of this, is the Conservative attack on their real enemy, Thomas Mulcair?

It's not like they don't have a reason to attack. According to the latest national polls, the Conservatives are no longer merely tied with the NDP. For the first time ever, the New Democrats actually are ahead of Stephen Harper's party.

But still, the Cons do not attack. Apart from a poorly conceived swing at Mulcair's caucus, only silence emanates from the Harper war room. No one knows why. Here's one theory: With the Liberals, all of the Conservative attacks were centred on character, not policy. The Tory ads took something that was personal to a succession of Grit leaders, and made it political. But with Thomas Mulcair? Nothing.

It is all very odd. The Cons have nothing to fear from the third-place Libs, yet attack; from the Dippers, there is now much to worry about, but they do nothing. Why the change in strategy? The likeliest explanation is the Tory war room has yet to settle on a character-based attack that will work. Until then, Mulcair should enjoy his holiday from pain. It's pleasant. But it isn't going to last.

The attack is coming.