Comedian Rick Mercer describes himself as "obsessed with politics" and his political rant is one of the most popular segments of Rick Mercer Report, his CBC-TV show that begins its 10th season Tuesday.

Mercer is also marking another milestone on Tuesday: publication of his book A Nation Worth Ranting About, a collection of his humorous musings on elections, politicians and hypocrisy in the highest reaches of power.

"Comedy can be a very devastating tool and you have to be aware of that," Mercer said in an interview on CBC's Mansbridge One on One.

It’s also cathartic, he says, adding that he knows many Canadians at home who rant at their radio or TV screens.

According to Mercer, Canadians are self-deprecating and have an admirable sense of humour — qualities that account for the popularity of that particular segment of his show.

Colourful politicians on the wane

It was Canada's colourful political characters — not just premiers but also cabinet ministers of all stripes who voiced opinions and spoke freely — that first sparked Mercer's interest in politics.

However, that kind of politics seems to be fading, he says, noted for instance that the federal Conservatives refer to their administration as "the Harper government," as if there was only one person behind it.

"I think politics has changed a lot and I think things are getting worse. I’m a glass-half-full kind of guy and when I look at what’s happening on Parliament Hill, then things are worse," he said.

But that doesn't mean he can't have a laugh about it, Mercer noted, as he described how he creates his rants.

"A good rant is short and that’s really my hardest job: cutting it down to a minute and a half. I never like to break the two-minute mark. It’s gotta have an opinion —  nine times out of 10, I try to make them funny. Sometimes they’re not. It’s usually gut reaction. It's a gut reaction to a situation," Mercer said.

"I have so much fun on the show. My show is not an angry show, but some of the rants are angry — they come from an angry place," he said in an interview with Q.

Mercer writes his rant the night before he tapes it and they’re filmed in a Toronto alley notable for colourful, "artist-friendly" graffiti that changes from week to week. Recording there is always an uncertain process: he could stumble over his words, a loud truck might drive by or a passer-by could try to speak to him mid-take.

"I have done them in one or two [takes], but then when that happens I don’t believe it, so I keep going. But I’ve done 30 and 40 and 50 and 60, because of all the various factors," he said.

Newfoundland's humour

The comedian, who grew up in St. John’s, says humour is an important part of Newfoundland culture.

"There’s a lot of funny people in Newfoundland. I remember had a lot of funny teachers. My mother was funny. My family is pretty funny. Newfoundland is a bit different: if you’re not funny, it’s frowned upon in a way," he said.

Mercer performs a live show Monday evening at Toronto's Princess of Wales Theatre to celebrate the release of A Nation Worth Ranting About. All proceeds are earmarked for his favourite charity, Spread the Net.