IN CONTENTION | TOM O’NEIL

To handicap the acting races, Oscar pundits shouldn’t rely merely on stars’ popularity, buzz and critical reaction. They must scrutinize academy members too -- their long-standing biases and voting trends.

LEAD ACTOR

Richard Jenkins, “The Visitor”

Frank Langella, “Frost/Nixon”

Brad Pitt, “The Curious Case of

Benjamin Button”

Mickey Rourke, “The Wrestler”

Sean Penn, “Milk”

Spotlight: Voters like nominees who portray real-life people, and this year there are two: Sean Penn as gay-rights activist Harvey Milk (“Milk”) and Frank Langella as Richard Nixon in “Frost/Nixon.” Their odds of winning are hiked because their films are also up for best picture, the winner of which usually claims an acting award (Russell Crowe in “Gladiator,” Dustin Hoffman in “Rain Man”). The 13 nominations that “The Curious Case of Benjamin Button” received might boost Brad Pitt’s chances, but his role is emotionally passive, as is that of Richard Jenkins in “The Visitor.” Sometimes voters go for that, and both actors are veterans overdue for recognition. However, voters usually reward the kind of firebrand roles played by Penn and Mickey Rourke (“The Wrestler”), who’ve split the derby’s early awards so far. Rourke’s own back story of overcoming personal demons may give him an edge with notoriously sentimental Oscar voters.

LEAD ACTRESS

Anne Hathaway, “Rachel Getting

Married”

Angelina Jolie, “Changeling”

Melissa Leo, “Frozen River”

Meryl Streep, “Doubt”

Kate Winslet, “The Reader”

Spotlight: Looks like Angelina Jolie has finally been forgiven for her tabloid life. She’s nabbed her first nomination since winning supporting actress for “Girl, Interrupted” in 2000. Or are voters trying to make up for the “A Mighty Heart” snub? Meryl Streep now has the most acting nominations in history (15), but she’s won only twice, and if Kate Winslet fails to win for “The Reader,” she’ll tie the record for most lead actress losses in Oscar history (six) without any victories. She has already claimed a SAG Award and Golden Globe for the role but those were in the supporting slot. Streep, meanwhile, won SAG and tied for the Critics Choice Award with Anne Hathaway, who fits the Julia Roberts Oscar mold: superstar of popcorn hits who crosses over into art-house fare. Melissa Leo was another breakout star of the art-house scene this year, earning nominations from Film Independent’s Spirit, SAG and Critics Choice awards.

SUPPORTING ACTOR

Josh Brolin, “Milk”

Robert Downey Jr., “Tropic Thunder”

Heath Ledger, “The Dark Knight”

Philip Seymour Hoffman, “Doubt”

Michael Shannon, “Revolutionary Road”

Spotlight: Most Oscar pundits say Heath Ledger is the front-runner, but beware. Of the seven actors who’ve been nominated posthumously in the past, only one has won: Peter Finch (“Network”). Still, Ledger has swept most early awards, so it looks like the Joker may get the last laugh. Best odds for the upset: Josh Brolin, who wowed moviegoers this year by giving a dead-on impersonation of George W. Bush in “W.” in addition to his nominated role as the killer Dan White.

Upsets at the Oscars happen most frequently in these supporting categories, and comedy is most often honored here. That’s where Michael Shannon and Robert Downey Jr., respectively, become possible choices. Philip Seymour Hoffman has a secret edge in this race. He’s really got a lead role in this supporting category -- that usually helps -- but there’s real doubt whether he can pull off an upset, considering the Ick Factor of his role as a priest accused of child molestation.

SUPPORTING ACTRESS

Amy Adams, “Doubt”

Penelope Cruz, “Vicky Cristina

Barcelona”

Viola Davis, “Doubt”

Taraji P. Henson, “The Curious

Case of Benjamin Button”

Marisa Tomei, “The Wrestler”

Spotlight: With Kate Winslet’s role in “The Reader” promoted to the lead race, that boosts the hopes of Penelope Cruz, who has two other advantages: She swept early awards from the New York critics, L.A. critics and National Board of Review, plus she has a flashy, eccentric role in a flick by Woody Allen, who specializes in delivering victories in these supporting races (Michael Caine, Mira Sorvino, Dianne Wiest). But don’t underestimate Marisa Tomei, who pulled off a jaw-dropping upset for “My Cousin Vinny” in 1993. Shockeroos happen frequently in this category, which bolsters the hope of Amy Adams, previously nominated for “Junebug” (2005), and Taraji P. Henson, who had strong early buzz. But Viola Davis probably has the best odds for a long-shot win. “Doubt” audiences have been blown away by her performance.