For some Academy members, voting in this category might end up being simply a process of elimination. Veteran actor Alec Baldwin earned his first-ever nomination as the menacing casino boss in ''The Cooler,'' but savagery, however convincing, didn't do the trick for ''Sexy Beast'''s Ben Kingsley two years ago. After being overlooked for ''Amistad,'' Djimon Hounsou made the list this year as the ailing neighbor from ''In America,'' but the role isn't as fleshed out as some of his competitors'. Ditto ''The Last Samurai'''s Ken Watanabe, whose noble swordsman lacks a big whopper of a scene. And Benicio Del Toro, who won this race in 2001 for ''Traffic,'' might lose points from voters who find ''21 Grams'' too bleak. That leaves ''Mystic River'''s murder suspect Tim Robbins, who brings spectacular spookiness to the film's most enigmatic character. After taking home twin supporting- and lead-actor trophies at the Golden Globes and Broadcast Film Critics awards, Robbins and costar Sean Penn could very well do it again on Oscar night.