The problem is that White House Chief-of-Staff Bob Alexander (Frank Langella) can't face bringing in Vice President Nance (Ben Kingsley). As far as he's concerned, the Oval office is his to command; he made Mitchell what he is and nobody's going to take away his power and influence without a fight. Unfortunately the only thing that Mitchell is anymore is a vegetable. Thus Alexander hits on a cunning idea with Alan Reed (Kevin Dunn) - why don't they draft in Kovic and use him as a temporary front? After buying themselves some breathing space, they can get rid of Nance, kill off Mitchell and slide Alexander into the hot seat. A classic piece of political manipulation.
Convincing Kovic to help them break the law is a touch tricky, though a measured call to his patriotic spirit reaps success. Hiding the deception from First Lady Ellen (Sigourney Weaver) isn't a problem because the couple is estranged, barely on speaking terms let alone sleeping together. The President's bodyguard Duane Stevenson (Ving Rhames) is privy to the secret, which is a great help with their biggest liability - Kovic himself. He may be a spitting image of their invalid leader but he sure doesn't act like him, showing off the politically unsound feature known as a heart at every opportunity. If only they knew that this was the least of their problems.
Despite sounding ripe for the over-blown, sickly-sentimental Hollywood treatment, Dave is actually a reasonable pleasant comedy. The fictional structure of one ordinary man going up against big business/government has been used countless times before, with varying results. Fortunately the tone is kept fresh and light in Dave, allowing the basically idealistic story to sweep away the great number of implausibility's that keep popping up. The script is averagely amusing, if rather predictable, maintaining a steady flow of chuckle-some moments (as opposed to brief flashes of side-splitting hilarity).
The factor which really sets Dave apart is the high quality of the acting, rather than the characters themselves. Kline does an excellent job of initially appearing as the reptilian President then switching adeptly to his alter ego Dave, a man who cares. There are a couple of scenes where technical trickery allows Kline to appear with himself but mostly it's the nuances of his performance which sets the characters apart. Weaver is equally convincing as the principled lady who has come to despise her loathsome husband, unsure whether the sacrifices were worth it. Her gradual realisation of the duplicity is well handled, though their growing attraction is pure Hollywood schmaltz. The remaining cast members are far more lightly sketched, though Rhames comes across sympathetically and most acquit themselves adequately.
Dave won't change the world by any means and it does become a bit too sweet by the end, but this doesn't ultimately matter. Approached in a light-hearted frame of mind, this is an undemanding satire lit up by a stream of contemporary cameos.