THE SPECIAL RELATIONSHIP. 9 p.m. Saturday, HBO.

BEFORE HE was introduced to fans of NBC's "30 Rock" as the man Liz Lemon (Tina Fey) seemed destined to settle for, British actor Michael Sheen had developed a small sideline based on his likeness to Britain's former prime minister, the charismatic and controversial Tony Blair.

Fey, herself the bemused beneficiary of a resemblance to a politician, could probably identify.

But where Fey's "Saturday Night Live" impersonation of Sarah Palin has been played for laughs, Sheen's portrayals have been in dramas, all written by Peter Morgan (who also wrote "Frost/Nixon," in which Sheen played the talk-show inquisitor to Frank Langella's Nixon).

In the 2003 film "The Deal," which came to HBO in late 2007, Sheen was the Labour Party friend and rival to another future prime minister, Gordon Brown. In "The Queen," he was the new PM to Helen Mirren's Queen Elizabeth II as they clashed - ever so gently - over the royal family's response to the death of Princess Diana.

On Saturday, HBO presents "That Special Relationship," in which Sheen plays Blair to Dennis Quaid's Bill Clinton, a pairing that puts Quaid at an automatic disadvantage in his own country, where Clinton's face and mannerisms are so much better known.

Quaid does a respectable job in a relatively thankless role, Clinton in Morgan's view having been the less sincere partner in the relationship between the baby-boomer leaders, a political friendship that, like so much in that period, was eventually tested by the Monica Lewinsky scandal.

Not only is Sheen on familiar ground with Blair, he's once again paired with Helen McCrory, reprising her role from "The Queen" as the prime minister's wife, Cherie.

Which makes it all the more remarkable that the one performance in "That Special Relationship" that required not even a moment of mental adjustment was Hope Davis' as first lady Hillary Clinton.

Playing a well-known figure is about much more, and sometimes about much less, than simple impersonation. But Davis manages to look and sound so much like the real Hillary that she transcends whatever bar lies between her and a skeptical viewer.

She's here and she's Hillary. Get over it. Maybe some screenwriter will take the kind of interest in the secretary of state's life story that Morgan appears to have in Blair's, and Davis can start her own sideline.

Morgan, though, might want to think about moving on. His formula, which juxtaposes larger-than-life real people at key moments in their careers, strains a little under the weight of the Clinton presidency and its baggage.

Yet it's always interesting to catch a glimpse of America as others see us: When Hugh Grant's prime minister stood up to Billy Bob Thornton's uncouth U.S. president in "Love Actually," it probably said as much as any comedy could about how some Britons were feeling about the so-called "special relationship" between our countries, and without even mentioning the war in Iraq.

Blair would eventually have to forge a relationship with another boomer president, George W. Bush, one that would cost him dearly as a politician and help transform him into a far less sympathetic figure.

I'm not sure there's any greater appetite for that movie - would they call it "Coalition of the Willing"? - but if Sheen's up for another go at Blair, Timothy Bottoms does a pretty good Bush. *

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