Kevin Kline is perfectly cast as both Bill Mitchell, a self-centered, womanizing president of the United States (fictional, of course), and his all-American nice-guy look-alike, Dave Kovic, in the simply titled "Dave."

Mitchell is a jerk, backed by a power-hungry chief of staff (Frank Langella) and a hapless communications director (Kevin Dunn). And he's estranged from the first lady (Sigourney Weaver), though they keep up appearances.

The plot here spins off the president's penchant for avoiding public appearances in favor of a tryst with his secretary. To accomplish this, doubles are used from time to time and Mitchell's staff has just found a doozy. Dave, who operates a local employment agency, is a dead ringer for the pres.

So, when Dave is asked to sub for Mitchell one night — just to exit a building and wave, nothing more — he happily accepts. But while he's doing this brief impersonation, the president has a stroke, suffered under the same stress that gave Sen. James Garner a heart attack in "The Distinguished Gentleman."

As a result, Dave is asked to stand in the president's shoes indefinitely. This gives the chief of staff a chance to have an even stronger hand in the country's direction, as he keeps Dave in the dark. But then something happens — Dave begins doing things. And we can't have that. So the chief of staff begins plotting the imitation president's downfall.

As written by Gary Ross ("Big") and directed by Ivan Reitman ("Ghostbusters," "Twins"), "Dave" is a savvy political satire. But it also manages a nice balance with its light romantic comedy side.

The casting is perfect, with Kline especially good as the gentle, sweet-natured nebbish of the title and Weaver just right as the icy first lady who gradually melts when she sees a change in her "husband." Langella is also quite good as the slimy villain of the piece and Dunn is amusing as the speechwriter who wants to do the right thing.

But every bit as entertaining are the supporting players — Ben Kingsley as the vice-president, Charles Grodin as Dave's best friend and especially Ving Rhames, hilarious as the president's stiff-necked bodyguard. Not to mention some 30 celebrity cameos, dominated by real-life politicians and newscasters. (Moviemaker Oliver Stone offers a hysterical inside joke.)

Simply put, "Dave" is a delight.

Putting it on the adult side are a sexual moment and an obscured nude scene of Kline in the shower, but everything here is much more restrained than you might expect. There is also some profanity and a couple of vulgar lines of dialogue, giving "Dave" a PG-13 rating.