Tina Fey visibly loses confidence as her romantic comedy "Admission" progresses. She lets Liz Lemon wackiness overwhelm more interesting instincts in playing what could have been her most substantive film character yet.

At film's start, Fey's character, Princeton admissions officer Portia Nathan, exudes competence, ambition and a dedication to giving the best shake to prospective students whose files she reviews.

Portia has painstakingly constructed an uneventful, respectable life with her professor boyfriend (Michael Sheen), in part to avoid the kind of extremes represented by her intellectually rigorous, emotionally removed feminist author mother (a captivatingly out-there Lily Tomlin).

Portia offers Fey, who is famously smart and in charge in real life, so many intriguing colors to play, and she plays all of them for a while.

She gives Portia edges of sadness in scenes with her mother, and a chilly cordiality in interactions with a colleague (Gloria Reuben) with whom she competes for a promotion. Portia flares with resentment when her affable but clueless boyfriend pets her head as if she were a dog.

Fey succeeds most in showing these moments as mere flashes in the broader picture of Portia keeping it together. She is a mature woman who has trained herself to handle her feelings.

Then, practically at once, the boyfriend leaves Portia for a loose-moraled Virginia Woolf scholar (is there any other kind?), and a cute alternative-school principal (Paul Rudd) tells Portia he believes a promising student, Jeremiah (Nat Wolff), is the son Portia gave up for adoption.

It's heavy stuff that Fey plays light. Instead of leaning into the new complexities facing her composed character, Fey goes goofy and scattered, like she's suddenly her "30 Rock" character, Liz Lemon.

Liz was a rather lovable neurotic, so you understand the choice. But Liz only worked in the universe of that show. When Portia gets goofy and scattered, she appears to have undergone a personality transplant. Fey and director/co-screenwriter Paul Weitz ("About a Boy") establish the character so well in the film's first 20 minutes that it's easy to identify a sudden leap out of character.

Losing her boyfriend and finding out about Jeremiah should rock Portia, but not to the degree that she dons a hoodie and pretends to be down with the kids at a college party.

It's shtick, and it's too easy.

The film is just as uneven. "Admission" starts out promisingly in showing a world unlike the worlds of most romantic comedies. Here, everyone is smart. Characters strive instead of slack as they do in most Rudd films.

Weitz illustrates the high stakes and hopes of the admissions process with a wonderful visual conceit. As Portia reads candidates' application essays, the teenagers in question appear, as if by magic, in her office. When she checks the "deny" box on their applications, the teens exit suddenly through a trapdoor in the floor.

"Admission" shot scenes at Princeton, and a sense of East Coast authenticity pervades the film. Portia and the professor's house looks like a place where bookish people live, with tons of wood accents but a lack of movie gloss.

The tone and story lack such solidity. Opportunities for moments between Portia and Jeremiah go wasted.

The boy knows only that Portia is a Princeton representative, not that she's also possibly his birth mother. But Wolff, awkward, curious and believably teenaged, makes Jeremiah vulnerable enough that the characters' interactions still might have been fraught were Portia's end of them better written. But Portia is at her most inappropriately comic with the boy.

Portia's possible bond with Jeremiah often takes a back seat to a tepid romance with Rudd's character.

The genial, perpetually relaxed Rudd appears to have a calming effect on Fey. And they are both good-looking, so it's not gross to see them together. But neither is it electric, and the romance seems shoe-horned in.

It's heartening, however, to see the always-appealing Rudd play a romantic lead without also learning his character's bathroom habits.

Tomlin is sharp, bright and odd, yet never broad, as a woman who thinks mothering means constantly instilling a sense of independence – including independence from her – in her daughter.

Tomlin says the nuttiest things with total conviction and a straight face. She does not oversell or vamp.

You wish her assurance would rub off on Fey. Tomlin rarely has compromised on screen to be more relatable, and here she is, at 73, still stealing movies.

ADMISSION

Two 1/2 stars

Cast: Tina Fey, Paul Rudd, Nat Wolff, Lily Tomlin, Gloria Reuben

Director: Paul Weitz

PG-13 (language and some sexual material)

110 minutes

Call The Bee's Carla Meyer, (916) 321-1118. Follow her on Twitter @carlameyersb.

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