NEW YORK – It seems appropriate that Benicio Del Toro takes a diplomatic stance when discussing the differences between playing a recognizable political figure and portraying a purely fictional character.

"There are ups and downs," says the actor, whose turn as Argentine revolutionary Che Guevara in "Che" is receiving widespread critical praise. "The up is that there is a lot of information -- a lifetime of information. That can be overwhelming at times, but that is an up because you don't have to create it."

"The down," he adds, "is the expectations, because people think they know the character. It shouldn't affect you as an actor, but inevitably it does."

Del Toro is in quite a crowded field this year, one of many actors in high-profile performances as real-life politicos. There is also Josh Brolin, who plays President George W. Bush, along with James Cromwell as his father, in "W."; Sean Penn as California's first openly gay elected politician Harvey Milk in "Milk"; and Frank Langella, whose portrayal of Richard Nixon in "Frost/Nixon" is, like the others, getting plenty of awards season buzz.

Although these are all meaty parts, playing political figures isn't a straight shot to Academy recognition. Oscar nods have actually been infrequent for these turns, with some notable exceptions, including nominations for Denzel Washington as Malcolm X in the 1992 film of the same name and Anthony Hopkins as Richard Nixon in 1995's "Nixon." And then there has been a smattering of Oscar wins, such as Ben Kingsley as Mahatma Gandhi (1982's "Gandhi"), and more recently Forest Whitaker as Idi Amin (2006's "The Last King of Scotland") and Helen Mirren as Queen Elizabeth II (2006's "The Queen").

This year, Brolin has a unique view on the subject because he plays two real-life characters from the world of politics; he also co-stars in "Milk" as Dan White, the city supervisor who assassinated Milk.

"With Dan White, I felt more pressure than with W.," he says, "because (director) Oliver (Stone) and I talked a lot about recreating the spirit of W., rather than making a carbon copy of him. Whereas with Dan White, I really wanted to get his voice down -- I tried to do an actual rendition of him."

Brolin says that both Stone and "Milk" director Gus Van Sant left it up to him to create the two characters, and he researched primarily by studying copious amounts of video footage. For "W.," Brolin also read 13 books on the president and constantly had his speeches on a loop "until I drove my assistant crazy," he says.

When actors study their political characters, they turn into veritable armchair therapists. "You can look at Bush or Obama and pick up character traits and little insecurities," says Langella, who also played Nixon in the stage version of "Frost/Nixon" and took home a Tony Award. "But they are junior league compared to Nixon, who was fabulously fascinating to watch."

Del Toro had more than enough time to prepare for Guevara. He spent seven years intermittently working on "Che," reading books, traveling to Cuba and Argentina. "Sometimes, when you play a part, you create a whole backstory," he says. "And it might be three pages long. But for Che Guevara, it would probably have to be 1,200 pages."

Del Toro says he and director Steven Soderbergh "wanted no one to tell us that what we shot didn't happen, even though a movie in itself is make-believe and we had to compress stuff. We wanted to make sure what we saw Che do in the movie was based on fact."

To find his character, Del Toro says his favorite tool was using photographs of the revolutionary leader. When the actor saw an image of Guevara being interviewed on an American television show and noticed he was wearing makeup, that inspired him to incorporate a scene in which his character asks for some powder before being interviewed.

Like Brolin, Del Toro felt most challenged when he tried to mimic his character, as he did when playing Guevara during a speech he delivered at the United Nations. "That speech is memorized verbatim in some Latin American countries," he says. "I listened to the tape over and over again." What was most difficult was speaking Spanish in the "scholarly" way that Guevara did. Del Toro stopped learning the language when he was 13, so he had some catching up to do.

It's not surprising that for many actors, discovering something intimate and private -- rather than something of public or global political importance -- is what most defines how they find their characters. For Langella, it was being in Nixon's childhood home for a day, on the grounds of the Richard Nixon Library in the little house that his father had built in Yorba Linda, Calif. Langella read the president's copy of Charles de Gaulle's "The Edge of the Sword," in whose margins Nixon had written notes. And for Del Toro, it was something he learned about Guevara during a trip to Argentina, where he met Guevara's younger brother, nephew and others who knew him.

"It was really moving to learn that when Che was 1 or 1-and-a-half years old, he had an asthma attack," Del Toro says, "and the whole family moved from one town to another -- like the distance from Los Angeles to San Francisco -- for the benefit of this kid. There's something about that sense of love, family and protection that really vibrated in my brain and stuck with me through the making of the movie."

But like most actors, Del Toro was happiest when he could just react, as he could in scenes with his co-star Demian Bichir, who plays Fidel Castro. "Demian had the attitude, the presence, the intensity," Del Toro says. "He dunked it. It was easy to play the naive Che with him and to shave off a few years. His presence was so strong."

And yet, Del Toro admits, even with all the preparation and close study of the man, he still felt that becoming Guevara was like "being in a pool and swimming toward the edge, but the edge kept moving further away." (Del Toro says he was grateful that his next turn was as the very fictional title character in the upcoming "The Wolf Man." "It was a relief," he says. "It was a great way to shed the skin, because with the Wolf Man, anything goes.")

Brolin shares the sentiment: "I never felt like I was getting it," he says of becoming Bush. "I never felt that -- ever, ever, ever."