Four years ago this fall, during the U.S. election campaign that would send Barack Obama to the White House, Sarah Palin made a mistake.

As historians are aware, Palin would go on to make a great many mistakes. Her name would become so synonymous with political misstatements and miscalculations, in fact, that her party would eventually come to treat her like political kryptonite. But back in 2008, the former governor of Alaska — and the then-Republican vice-presidential candidate — was still a pretty big deal. Conservatives swooned over her. Pundits sang her praises. She was arguably more popular than the Republican presidential nominee, John McCain.

Some Democratic Party smart alecks poked fun at her, however, and Palin didn’t like it so much. The Democrats ribbed Palin for her apparent lack of experience, particularly as a small-town mayor in Alaska. So Palin struck back.

At the Republican convention in St. Paul, Minn., to thunderous applause, Palin said: “I guess a small-town mayor is sort of like a community organizer. Except that you have actual responsibilities.”

This was a swipe at the employment history of Barack Obama, of course, and the GOP crowd loved it. Obama was soon forced to defend the period in which he had worked as a community organizer in Chicago in the late 1980s. As the above-noted historians will remind us, the insult didn’t really work so well, did it? Obama — a young black man, the son of a single mom and, yes, a community organizer — would go on to be president of the United States of America.

And Palin? Well, her party discouraged her from attending its gathering in Tampa in August. And she does reality TV. To a lot of U.S. conservatives, working as a community organizer didn’t seem like a real job. To them, it sounded like the sort of thing that socialist rabble-rousers and pointy-headed liberal elitists would do. So they mocked Obama endlessly about it.

Up here, the Republicans’ ideological cousins are busily running the same sort of smear campaign against Justin Trudeau, who last week announced that he is seeking the leadership of the Liberal Party of Canada.

The Conservative Kill Machine (CKM, for short) promptly got to work, distributing focus-grouped talking points about how Trudeau was a “lightweight.” Evidence of his light-weightedness was easy to provide, said the CKM: Trudeau had only been — wait for it — a school teacher.

A school teacher! If you have only been a school teacher, it was expressed and implied, you are unfit to run a country like this one.

Unlike Stephen Harper, that is, who had previously been a lobbyist for a shadowy conservative group that has been against public health care, labourers and Vietnamese refugees. And a one-term MP for a party that never won government. And, er, that’s it.

It is a tried and tested formula, and that is why the CKM likes it. Michael Ignatieff, out-of-touch academic. Stephane Dion (ditto). Paul Martin, rapacious, tax-dodging shipping baron. And so on.

If you pay close attention to what conservatives like Palin and Harper say about their political opponents, snide remarks and insinuations about a liberal’s employment history are never too far from the surface. They do it all the time. And they’re doing it again with Trudeau.

There’s a risk in such a strategy, however. As Palin discovered, quite a few people — younger people, newcomers, women — considered Obama’s experience as a community organizer to be, you know, good. They voted accordingly.

The same goes for teachers like Trudeau. Those of us with kids know that teachers, on balance, have better reputations than one-term Reform MPs who hate public health care.

So, knock yourself out, CKM. It didn’t work for Sarah Palin, and it won’t work for you.

— Kinsella’s Fight The Right was published this month by Random House.