I've really enjoyed what little I've seen by Tina Fey and Amy Poehler -- mostly online recaps of their Election 2008 coverage, but still, it shows comic talent. So when I was home convalescing after knee surgery, we picked up their recent buddy film, Baby Mama, to pass a little time.

Sadly, it seems they should have kept making hay of Sarah Palin's political inadequacies, because this film -- though rife with potential and boasting a fine supporting cast -- was 99 minutes I could have better spent contemplating the pain shooting down my leg.

The plot is simple: successful businesswoman Kate Holbrook (Fey) feels her biological clock ticking at age 37 so, unmarried and unable to conceive through artificial means, she buys the services of feisty surrogate mother Angie Ostrowiski (Poehler) to carry to carry Kate's fertilized egg. But Kate and Angie are two peas from pods on the opposite ends of the garden, and predictable hijinks ensure. (OK, they weren't all predictable. I didn't anticipate the scene where Angie peed in Kate's sink.)

Jokes fall flatter than Kate's seemingly infertile tummy. Stereotypes abound; blacks, gays and wiccans are among those who will probably be offended at one point or another. And the story keeps building to laughs that the movie just can't -- mind the pun -- deliver.

It's a shame, because I know Fey and Poehler can both do better. I also expected more from the supporting cast, which includes Greg Kinnear as an easygoing juice-monger and Kate's potential love interest, Sigourney Weaver as the mogul of a lucrative surrogate-mother enterprise and Steve Martin as a narcissistic health-food guru. Weaver and Martin pull off much of the genuine humor in this film, while Kinnear puts sincere effort into a fairly bland and thankless role.

Meanwhile, the two leads slog through material that seems like it should be funny but isn't. Given the people involved, I expected a smart, well-written comedy that offered some touching insights into society along the way. Instead, they went for cheap chuckles -- and failed to earn them.