A misbegotten attempt to renew the charms of vintage, battle-of-the-sexes romantic comedy, "Continental Divide" falls apart in every crucial respect: plotting, characterization, casting, direction.

Costars John Belushi and Blair Brown never come close to charming their way out of flimsy roles, but even if screenwriter Lawrence Kasdan had provided sound characterizations while trying to evoke the spirit of a Katharine Hepburn-Spencer Tracy comedy, it appears doubtful that these performers would ever achieve a winning or glamorous rapport.

Belushi and Brown show no signs of clicking as a team. One detects no special sexual or temperamental chemistry between them, no feeling of fundamental emotional attraction and compatibility.

In all fairness to them, the material in "Continental Divide" is so poorly contrived and rationalized that it would require a classic romantic comedy team to finesse the problems.

Belushi and Brown are meant to confirm the principle that opposites attract. Unfortunately this set of opposites is so divergent and their affair so feckless that it becomes impossible to swallow a pleasant romantic fiction. Belushi's character, Ernie Souchak, is a muckraking columnist for the Chicago Sun-Times. Brown's, Nell Porter, is a distinguished, reclusive ornithologist dedicated to the study and preservation of the American bald eagle.

Supplied with leaks by a lawyer, who works for a crooked alderman named Yablonowitz (Val Avery), Ernie has been ragging the politician in his column. When Ernie is roughed up by a couple of thugs, his solicitous editor, Howard McDermott (a fairy-tale character impersonated by Allen Goorwitz), concludes it would be wise to transfer the wise-guy scandalmonger out of town for a spell. For the sake of the plot, Ernie is persuaded to take a hike in the Rockies to secure an exclusive interview with Nell, who is notoriously hostile to the press.

Deposited on the doorstep of Nell's secluded cabin, Ernie inexplicably worms his way into her affections despite misrepresenting himself for starters and then acting like an incorrigible, burdensome klutz. Kasdan repeatedly fails to establish a credible basis for romantic attraction. The episodes in the Rockies illustrate little except Ernie's foolishness and incompetence when transposed to God's country. Far from becoming a plausible suitor or mate, Ernie suggests an overgrown, oblivious foundling Nell is obliged to protect from harm.

Ernie appears to such an extreme disadvantage that you begin to wonder if the screenwriter is revealing an embarrassing streak of masochism. The protagonist of "Body Heat" also found himself at a peculiar disadvantage with the woman he fell for, but at least you could believe in his potency and mental resourcefulness. You're not so sure about Ernie's capacities. The tubby, slothful, rather infantile Belushi never looks like delectable masculine bait to begin with, and Kasdan doesn't endow Ernie with strength of character or an irresistible personality.

For romantic-comedy purposes, it seems self-defeating to depict your leading man as a constantly humiliated and battered suitor. It's far more excruciating than amusing when Ernie discovers Nell dallying with a mountain-man lover or finally scores with her himself while convalescing from wounds inflicted by a mountain lion. If anything, one might jump to the conclusion that the heroine was a trifle kinky from cabin fever.

"Continental Divide" needs the balance found in an astute romantic comedy like "Pat and Mike," where the Hepburn and Tracy characters sprang from different social backgrounds but had something to offer each other both professionally and emotionally. The basis of the appeal, however amusing or worthy the characters seem as individuals, is the sense of a natural union being forged or confirmed that ultimately stirs the spirit and exalts the genre.

Only mental laziness or wishful thinking could sustain the delusion that Ernie and Nell are meant for each other. Under the circumstances, Kasdan's arbitrary happy ending is downright depressing. A pity such a lovely title should disclose such a motley imitation of classic romantic comedy.