TORONTO - Rich Little says he's perfected his impersonation of U.S. President Barack Obama, but admits it took him awhile to nail it.

The Ottawa-born funnyman, in Toronto on Saturday to perform at a charity event, is known for his spot-on renderings of former U.S. presidents Richard Nixon, Ronald Reagan and Jimmy Carter.

Other U.S. commanders in chief, however, have presented a challenge.

"Gerald Ford was pretty tough. I finally got it but he was just on his way out," said Little.

"Some presidents are just larger than life and they're easy to do like Nixon and Jimmy Carter and Reagan. They're very interesting, different people. Barack Obama, maybe George W. Bush and Gerald Ford are a little tougher."

It's been a few years since Little has tried to mimic a politician from north of the border.

"I haven't done a Canadian prime minister in years because I don't know too much about what's going on here," he said.

Still, the comedian said he'd consider attempting a Stephen Harper impression -- if he got a chance to perform in Ottawa.

"I'd like to play my hometown but I never get any offers," said Little. "I still have a lot of friends there. It'd be kind of nice to go home and do a show.

"I'd give (Harper) a shot. I'd listen to a few tapes and see if it was possible. I think he would be tough to do. I'm not aware of his mannerisms.... He'd be another Gerald Ford."

Little first began honing his craft as a kid imitating teachers in school. He later worked as a radio DJ and got his big TV break in 1964 when he did impressions on "The Judy Garland Show."

He went on to become a TV regular, appearing on numerous variety shows as well as a stint on the classic game show "Hollywood Squares."

His website lists dozens of the stars he has impersonated, including Paul Lynde, Carol Channing, Orson Welles, Johnny Carson and, one of his most famous voices, Jimmy Stewart.

The Stewart impersonation, Little said, was the first he ever did. The voice is still so popular that he recently developed a one-man Jimmy Stewart tribute show and began touring it last year.

Slipping into Stewart's halting voice, Little said he once approached the late actor with the idea, but was met with skepticism.

"He said: 'But Rich, the way I talk, it, uh, it could be, uh, four, four hours long.' I said: 'Well Jim, I'll speed it up a little bit."'

Little, who turns 72 next month, said the show will hit Broadway next year and he hopes to one day bring it to Canada.

And while many of the celebrities Little impersonates have long since passed away, the comedian said that doesn't seem to be much of an obstacle for audience members.

"Sometimes I'll do a show and the kid will be laughing, a young kid in the audience, and I'll say: 'Did you know anybody I imitated?' This one kid a couple of weeks ago said: 'No, I didn't know anybody you did, but boy are you funny!"'

Although he does have some modern celebs on his voice roster (he does a mean Uncle Phil from "The Fresh Prince of Bel-Air"), Little notes that many of today's stars are more low-key and are tougher to do.

"How are you going to do Brad Pitt?" asked Little. "Yell at Angelina, I guess."