"The Rat Pack" qualifies as a television event, but a rather minor one. HBO's movie looks at a tiny moment in American cultural and political history and tries to find it momentous and resonant. The raw materials don't support such grandiose ambitions, and the dead earnestness finally becomes deflating.

Watching it is like having a hangover without the fun of getting happily plastered in the first place.

The film, premiering on HBO at 9 tonight, purports to evoke the swingin' Frank Sinatra years when "the chairman of the board" really did seem to have a board to be chairman of -- a gang of cronies that included Dean Martin, Sammy Davis Jr. and Peter Lawford. They swaggered and tottered through what then seemed a merry era but which the movie finds tres triste and tragique.

Its main fixation is Sinatra's thwarted campaign to be respectable and accepted by the Kennedy White House, plans that go thunderously awry in the movie's penultimate scene. Although Sinatra worked hard to help Kennedy get elected -- including, says the movie, getting mobsters to turn out Teamsters in West Virginia and having dead voters cast ballots in Chicago -- patriarch Joe Kennedy thought rat-packing was a bad image for his sons Jack and Robert and put the kibosh on all that ring-a-ding-ding.

Ray Liotta seems too soft an actor to play Sinatra, getting poignancy out of the portrayal but not much visceral impact, and never once looking like a man capable of making some of the greatest pop music of the century. Joe Mantegna is a lot more successful at summoning up the image of Dean Martin, sometimes entering a room in such a Martinesque way that you'd swear for a second it was Dino himself brought back to life-o.

But the Martin character is a one-noter, a kind of philosopher-poet who sits around making wry remarks and not getting very involved in the drama.

As Davis, Don Cheadle makes the most of arguably the most powerful scenes in the film. Sad as it is to recall now, Davis's engagement to a white actress, Mai Britt (nicely played by Megan Dodds), caused a racist uproar at the time. Further, Britt tells Sammy that not all the onstage jokes about his blackness are amusing: "They're making fun of you, not with you."

The movie has a number of set pieces and montages and the wackiest is a dream sequence in which Davis faces a mob of bigots and Nazis by singing "I've Got You Under My Skin" to them. It doesn't quite work, but you have to admire the audacity of it. Unfortunately, while Cheadle does fine in the straight drama scenes, his dancing is klutzy where Davis's was lithe and weightless.

Most of the action takes place in and around 1960. Sinatra is master of his own show-bizzy domain but craves something more, something classier. As depicted in this movie, though, the Kennedys weren't any classier than he was, with John Kennedy such a hound as to make Bill Clinton look virtually chaste -- sleeping around not only with Marilyn Monroe but with Judith Campbell, mistress to mobsters. During a coital montage, Sinatra is seen in bed with two broads -- that is, women -- at once.

Dan O'Herlihy makes a properly frightening and arrogant Joe Kennedy, issuing orders from his lair as if a mobster himself. He sends word through Lawford, for instance, that Sinatra must cancel plans to be best man at the Davis-Britt wedding because it will hurt JFK's chances in the South. The wedding is postponed until after the election so the issue becomes moot.

Next to Mantegna's Dean Martin, the most uncanny impersonation in the picture is Deborah Kara Unger's brief knockout performance as Ava Gardner, Sinatra's one true love who taunts him sexily with a sultry toreador dance in the bedroom. But Sinatra is busy on the phone with one of his gangster pals, and so Gardner walks out on him again, this time for good.

Director Rob Cohen goes for darkness in the literal as well as figurative sense. Even characters bathed in the glow of spotlights onstage seem somehow shrouded and dim. Offices look like funeral parlors. The look is too dark and the film too dank, with Sinatra's rat pack finally seeming less the subject of the movie than its victim. CAPTION: Ray Liotta achieves poignancy but not much visceral impact as Frank Sinatra. CAPTION: Joe Mantegna (as Dean Martin), Angus Macfadyen (Peter Lawford), Ray Liotta (Frank Sinatra), Bobby Slayton (Joey Bishop) and Don Cheadle (Sammy Davis Jr.) in "The Rat Pack."