Just a week after the death of Christopher Reeve (search), Warner Bros. is poised to fill his old Superman (search ) tights with an obscure but hunky 25-year-old TV actor.

Brandon James Routh (search ) is the studio's choice to play Superman in an untitled $200 million blockbuster set to begin filming early next year in Australia, Latino Review and several entertainment Web sites reported yesterday.

Warner Bros. wouldn't comment on the reports, but sources confirmed Routh, aka "B.J." Routh, was in talks for the role that rocketed the then-unknown Reeve — who, like Routh, cut his acting teeth on a TV soap opera — to international stardom in 1978.

Several established actors — including Josh Hartnett, Jake Gyllenhaal and Brendan Fraser — reportedly passed on the role, fearing they would become typecast as Superman, as did Reeve (who made three sequels) and George Reeves, the actor who played the comic-book hero on TV in the 1950s.

Most recently, Jim Caviezel, who played Jesus in "The Passion of the Christ," had actively campaigned to portray the Man of Steel.

But director Bryan Singer said that unlike his predecessors on the project, he was committed to casting a relative unknown.

Routh is believed to have beaten out such other low-profile contenders as Jason Behr ("Roswell"), Henry Cavill ("The Count of Monte Cristo") and Jared Padalecki ("New York Minute") for the highly sought role.

"Wow, I guess casting an unknown is best really," said Kevin Smith, who wrote a draft of the long-in-development epic several years ago, when it was going to star Nicolas Cage and be directed by Wolfgang Peterson, and then Tim Burton.

"Charlie's Angels" helmer McG had most recently been set to direct, but stepped out earlier this year when Warner Bros. refused to let him shoot in North America for budgetary reasons. He was replaced by Singer, who shot the first two "X-Men" movies.

Iowa native Routh, who appears in a Superman costume in a photo taken last Halloween and posted on his Web site, has made guest appearances on such sitcoms as "Will & Grace" and "Gilmore Girls." The 6-foot-2 former model had regular roles on MTV's late-night soap opera "Undressed" and the daytime soap opera "One Life to Live."

When he was fired from the soap two years ago, Routh posted an angry account on his Web site blasting the show's producers.

"Instead of being open and honest with me, they were conniving and malicious," he wrote.

He removed the message several hours later — and apologized for it.

Superman won't be Routh's movie debut — he has a small role in a low-budget thriller called "Deadly" already in the can, awaiting release next year.

The new Superman movie — due out in 2006, the first since "Superman IV: The Quest for Peace" flopped in 1987 — reportedly has the Man of Steel returning to Earth after a six-year absence to do battle with evil.

No other casting choices have yet been revealed, but recent Internet speculation centers on Mischa Barton as Lois Lane.

"I heard Singer's thinking about [Kevin] Spacey as Lex Luthor, which is awesome," Smith told The Post.