Even before his recent stint in rehab became news, it was obvious that these are not high times for Robin Williams. The actor may be one of the most annoying comic presences on the screen, by turns compulsively hyperactive and beagle-eyed maudlin. Twenty years ago, this kind of manic-depressive caricature seemed novel. But even the most animated charm and fiercest wit becomes a grind when locked into constant fourth gear.

Eventually, perhaps, Mr. Williams began to get on his own nerves. Maybe that explains why he reversed polarity, playing psycho in a series of films — a killer in “Insomnia,” a lonely stalker in “One Hour Photo” — that, unfortunately, are now memorable only as the “Robin Williams goes psycho” movies. Of course, it wouldn’t explain last year’s “RV.”

Mr. Williams returns to more familiar form in “Man of the Year,” reunited with old hand Barry Levinson, with whom he enjoyed 1980s success in “Good Morning, Vietnam,” and 1990s failure in “Toys.” The premise appears timely, especially from the director of 1997’s astute “Wag the Dog,” which illustrated the concept of political “spin” in a way that made the film’s title into pop-culture jargon.

“Man of the Year” supposes what happens when a sharp TV comic with a bent for tart political observations decides to run for president, taking a cue from the popularity enjoyed by Comedy Central’s satirist in chief, Jon Stewart, during the 2004 campaign.

There’s a twist, also partially inspired by real events.The election introduces a new computerized system at the polls, which has a glitch. A corporate tech whiz (Laura Linney) makes the mistake of mouthing off about it, and is quickly assaulted, drugged, and discredited. Meanwhile, Tom Dobbs, the third party candidate played by Mr. Williams, improbably carries the tainted vote.

This setup could succeed in various ways, but it fails through sheer blandness and lack of a specific point of view. There are jokes about airport security and immigration, and rather stale jokes at that, but it must have been decided that any mention of the Bush administration, Iraq, or Hurricane Katrina would be too polarizing. So all the supposedly funny and pointed stuff candidate Dobbs gets to mouth, rallying the masses in a populist, tell-it-like-it-is wave of righteousness, feels absolutely fake and dishwater dull.

Mr. Levinson lavishes the screen with repeated second-unit shots of a campaign bus rolling down America’s endless gray ribbons of highway in a stale bid for verisimilitude. Or maybe he got some leftover footage from Aaron Sorkin’s attic. Everything is exactly that generic, making this just another flick that dispatches a comic figure to the White House because it can. Roll over Chris Rock, and tell Beavis and Butthead the news.

Ms. Linney nearly saves the show, which becomes compelling only when her whistle-blower goes on the lam, pretends to be an FBI agent, and connects with Mr. Williams as president-elect to inform him his victory is a sham.(It’s also a shame, since the candidate’s what-me-worry attitude proves a refreshing antidote to D.C. doublespeak, though such disclosures are hardly profound.)

Romance ensues; it’s probably only because Ms. Linney is nearly the best actress in North America that an audience can suspend disbelief for this portion of the story. Mr. Levinson has assembled a talented supporting cast (Jeff Goldblum, Christopher Walken, Lewis Black) that has to do little more than punch the clock.Yet Ms. Linney gives her character as much empathetic, juicy realism as she did in “The Squid and the Whale.” Her scenes with Mr. Williams, whose rubbery, sad-sack face recalls that of Jack Kerouac in his fading years, have you believing him, too.It’s like they both stumbled into a puddle of human decency that the screenplay had been flailing to contrive.

Those moments, however fleeting, suggest some other possibilities for Mr. Williams, though they aren’t nearly enough to make “Man of the Year” worth anyone’s time. Fans of Ms. Linney can take heart, though. She probably banked enough salary baking this turkey to subsidize her performances in another half-dozen independent films by unsung directors who can profit from her presence.