Release date: Dec. 9U.S. distrib: Focus Features Oscar alumni: Ang Lee (foreign-language film, “Crouching Tiger, Hidden Dragon”); Manlio Rocchetti (makeup, “Driving Miss Daisy”) Riding a wave of awards buzz that began at Toronto, Venice and Telluride — and stoked by its winning the Golden Lion at Venice — Western love story “Brokeback Mountain” is one of the leading Oscar contenders of the year. Ang Lee’s film is taken from Annie Proulx’s devastating 1997 New Yorker short story, published in her collection “Close Range.” Starting in the early ’60s, it tells the tale of two cowboys (Jake Gyllenhaal and Heath Ledger) who begin a torrid affair one summer tending sheep on a mountain for a Wyoming rancher. The men go their separate ways at summer’s end, each going on to marry women and raise kids. But when they run into each other years later, the feelings they thought they left behind come rushing back. The film dovetails nicely with the repressed passions that have touched most of Lee’s films, from the marriage-of-convenience comedy “The Wedding Banquet” through “Sense and Sensibility,” “Crouching Tiger, Hidden Dragon” and “The Hulk.” Another characteristic of Lee’s work is his mature handling of subject matter, taking his time to let the drama unfold organically. Dubbed “the gay ‘Gone With the Wind’ ” at the Toronto Film Festival, “Brokeback” moved many to tears at its screenings. Variety‘s Todd McCarthy called it “an achingly sad tale” about “men lucky enough to connect but forlornly unable to fulfill their characters and live according to their true natures.” Ledger, who has reaped most of the acting kudos so far with a performance that Entertainment Weekly’s Owen Gleiberman described as “gnarled, taciturn brilliance,” appears to be a strong candidate to receive his first lead acting nomination. Gyllenhaal is enjoying a banner year, too, with roles in “Jarhead” and “Proof.” If “Brokeback” momentum is strong enough, a Ledger nomination could mean his onscreen love pardner joins the list, too. Westerns have long been an Oscar staple, even winning picture awards in fallow years for the genre (“Dances With Wolves,” “Unforgiven”). Given award-winning “The Last Picture Show” author-screenwriter Larry McMurtry (with Diana Ossana) handling an adaptation that goes to considerable lengths to flesh out its source material, the Oscar writers branch is likely to look favorably on the enterprise. Tech credits are solid, too, with hot d.p. Rodrigo Prieto (“21 Grams,” “8 Mile”), a master at lighting harsh physical landscapes, on tap for his first nom, as is composer Gustavo Santaolalla, whose profile has risen considerably in the wake of his music for “The Motorcycle Diaries.” Also a factor is the Academy’s progressive stance on gay themes. William Hurt (“Kiss of the Spider Woman”), Tom Hanks (“Philadelphia”) and Hilary Swank (“Boys Don’t Cry”) have all won lead trophies playing gay characters, while others have been nominated. Today’s political climate could also affect the vote. If “Brokeback” becomes an op-ed movie, a conservative backlash might energize Acad members who would love to thumb their noses at the “Red State” blue noses. In a sense, “Brokeback” is the most powerful type of controversial film: the kind whose case for social change is made through the heart instead of the head. When it comes to swaying Oscar voters, social relevance and emotional pull is a potent combo.