Sarah Palin issued a statement the other day, demanding that HBO label its film Game Change, which chronicles the McCain/Palin 2008 U.S. presidential campaign, as a work of "fiction." She also asked supporters to donate to her political action committee and used the movie's trailer as bait.

Posturing? Certainly. As far as HBO knows, Palin and her team have not seen Game Change. In an online plea for donations, Palin's team tweaks the trailer to garner support. Showbiz tactics? Again, certainly.

This is what American politics, especially the Republican side, has become – outrageous posturing and showbizzy machinations. Politics by press release, Tweet and trite, contrived attention-grabbing, media-savvy moments.

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Much of Game Change (airing Saturday, HBO Canada, 9 p.m.), a must-see, devastating portrait of Palin and the McCain campaign, is about the allure of celebrity and the injection of showbiz stratagems into U.S. politics.

But is it all true? Or is it fiction? "Yes it's all true," Danny Strong, the movie's writer and co-executive producer, said on the phone last week. "Everything in it is verified. The book on which it's based [the bestselling book of the same name, about several American presidential campaigns, by journalists Mark Halperin and John Heilemann]is based on eyewitness accounts. The book has not been debunked, as the Palin camp has claimed.

"Let me tell you something. The goal of the film wasn't to attack Sarah Palin or change anyone's mind about anything. The goal of the film was to talk about the process of how we elect our president, and here's the story, a pretty crazy story, in which a candidate was not vetted to be vice-president of the United States. She was not properly vetted, and we came very close to having a vice-president that perhaps wasn't prepared for that job."

Me, I remember well my first experience of Game Change. That evening in Pasadena during the January TV Critics Press Tour when HBO screened the film for several dozen critics, most of them American.

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As Game Change unfolded, there were giggles and laughter. Especially at the front end – viewers see John McCain (Ed Harris) and his advisers mull potential running mates. They acknowledge Barack Obama has great presence and a superstar glow. They need a counterpoint to run as vice-presidential candidate. There's a jaunty tone, and it produced laughter in the room. Even as the Palin character (Julianne Moore plays her superbly) entered the picture, all gee-whiz enthusiasm, there was giggling.

Then the laughing stopped, replaced by groans of embarrassment. Because the depth of Palin's ignorance of the world became clear. Palin didn't really understand why there was a North Korea and a South Korea. She clearly thought that Saddam Hussein was behind the 9/11 attacks. She needed to have Germany's role in the Second World War explained to her. She thought "the Fed" referred to the federal government, not the Federal Reserve. The Governor of Alaska is seen being as ignorant of the world as a small child.

How did it happen? Game Change suggests that in its enthusiasm to involve Palin and dent the Obama surge (Obama is described as a "celebrity" by McCain adviser Steve Schmidt, played by Woody Harrelson), Palin was vetted in a mere five days. Normally it takes months to thoroughly vet a VP candidate. All of Palin's baggage and ignorance came as a surprise to the McCain team. It was about getting the star candidate, the celebrity mom/governor on the ticket.

Nobody articulates this in Game Change, but there was a strong whiff of the ascension of reality-TV celebrity culture in the choice of Palin. Her ordinariness was authenticity epitomized, the equivalent to regular folks made famous by Survivor or American Idol.

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It's that torque of celebrity-obsession that truly informs Game Change. Watching it and indeed watching Sarah Palin on TV these days is a bewildering experience. There's a real Palin, the iconography of her public image – the hair, glasses and distinctive twanging speaking voice – intact. But we filter it through Tina Fey's uncanny parody, an act of mockery so devastating because it only heightens, slightly, Palin's authentic presence.

If Fey's work is an artist's rendition of Palin, Game Change is a reporter's account of the McCain/Palin campaign. And Julianne Moore's work is one of eerie mimicry. Perhaps the most subtly disorienting scene is when Moore, as Palin, sits and watches Fey playing Palin in Palin's disastrous interview with Katie Couric, played by Amy Poehler. The politician, the person with policy statements and plans for government, evaporates in this series of mirrors.

Moore has been careful in her conversations about playing Palin. Talking to critics back in January, she was nothing if not complimentary to Palin. "Her situation was a pretty extraordinary one. Somebody who had been involved in state politics was suddenly thrust into national and international politics," Moore also said Palin had "moments of sheer brilliance."

"I think the whole country took a collective gasp, saying, 'Who is she? Where is she from?' " Moore added. "She was so incredibly charismatic. Suddenly, here was this working-class mother who just popped out and seemed to be able to command the world."

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Indeed. That only underlines the complex cultural subtext to Palin's rise – she presented as "working-class mother," but she was a state governor and intuitively shrewd about her reality-TV-like charisma and impact.

At the end though, Game Change is terrific television, superbly crafted by Danny Strong and director Jay Roach. (They also collaborated to make Recount, the HBO movie about the Florida election recount in the 2000 presidential election and the Bush v. Gore case in front of the U.S. Supreme Court.) What sympathy that emerges for Palin is organic. What the movie indicts is the system and the tactics that led to her elevation.

You will be shocked by her ignorance, and appalled by her arrogance. You will be stunned by how close she came to a full-blown breakdown. You will need to remind yourself that it's all true. Here's the thing: It's about showbiz-in-politics but it's all real, all authentic.

Sarah Palin doesn't like Game Change. But it hardly matters to her. The movie increases her fame and impact, and as Game Change makes clear, Palin likes being famous. Game Change, Julianne Moore and Tina Fey only enable her.

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