It was nearly the exact midway point between the last election campaign and the current one when the federal Liberals gathered in Ottawa last March for their national convention. And almost to a man, they offered the same take on why they faced little risk of losing power.

So long as Stephen Harper was leading the Conservatives, they insisted, they had nothing to fear. If he'd managed to blow the last campaign, there was no way he was going win the next one. All they'd have to do is sit back, play it safe, and watch him self-destruct.

Clearly, it wasn't just the rank-and-file who were of that opinion. We now know those closest to Paul Martin felt the same way. And if the first half of the current race has taught us anything, it's that they underestimated their rival.

It's always a bad idea to attempt to run the same campaign twice against the same opponent. The Ontario Conservatives learned that lesson in the 2003 provincial election, when they assumed that Liberal leader Dalton McGuinty would be as inept as has been in the 1999 campaign. When a new and improved McGuinty hit the hustings, looking sharper and less mistake-prone, the Tories were caught flat-footed. Having assumed they could again convince voters their rival was "just not up to the job," they had no decent Plan B when McGuinty failed to live up to that billing.

Martin's Liberals are now in much the same situation - trying to go back to the well once too often, and finding it dry.

In 2004, after a disastrous first half of the campaign in which they mistakenly assumed the public shared their zeal for the Prime Minister (remember all those "Team Martin" campaign signs?), the Liberals salvaged a minority government by turning the spotlight on to Harper. Amid a series of nasty, well-focused attacks, the Conservative leader stumbled - sending out press releases accusing his opponents of supporting child porn, triumphantly touring Alberta and speculating on a majority government, and watching helplessly as a veteran MP embarrassed him with a taped attack on the Charter of Rights and Freedoms.

This time, the Liberals evidently figured they'd cut to the chase by focusing on Harper from the get-go. Forget about Liberal candidates plastering his face on their signs; even Paul Martin hasn't seemed especially keen to talk about Paul Martin, as evidenced by debate performances last week in which he was more keen to ask "questions" of Harper than to speak to his own policy positions.

Since neither Harper nor his candidates seem to be digging their own graves, the Liberals have repeatedly tried to hand them shovels. But whereas the Tories would have fallen right into Liberal traps in the past, they've stepped neatly around them.

The Liberals' proposed handgun ban was a prime example. Clearly, they were hoping that Harper would align himself with gun owners, ranting about property rights and alienating centrist voters. Instead, he took issue only with the meaninglessness of the Liberal pledge, not with the notion of restricting handguns - depriving the Liberals of the wedge issue they were seeking.

Much the same thing happened when Martin attacked the American environmental record, eliciting a hostile response from U.S. ambassador David Wilkins. The old Harper would have played right into Liberal hands, aligning himself with the Bush administration by accusing Martin of embarrassing us abroad. The new Harper played completely against type by admonishing Wilkins for intervening in our election -- then threw it right back at Martin by suggesting the PM's relations with the U.S. remind him of "the kid who was always name-calling from a safe distance" without actually being tough enough to engage in a fight.

Their more subtle attempts at derailing Harper having gone nowhere, the Liberals have wasted little time getting more brazen. Last week, they started digging up Harper speeches from eight years ago, while John Duffy used his space on this page to revive the old claims about a secret agenda on everything from Iraq to abortion. Now, apparent drafts of Liberal attack ads leaked yesterday suggest they intend to further ramp up the rhetoric in the campaign's second half - particularly by claiming Harper is in bed with separatists.

Barring the Conservative campaign getting a lot clumsier, it's hard to imagine the strategy paying off. With Harper much harder to paint as "scary" than he once was, the Liberals look like they're crying wolf one too many times.

As the campaign pauses for breath between Christmas and New Year's, the Liberals need to go back to the drawing board. Canadians will have all the warmed-over leftovers they can handle over the holidays; the last thing they need is for the Liberals to keep force-feeding them the stale remnants of the 2004 campaign.