Neil Patrick Harris has made all kinds of tracks since he became a national icon as TV's "Doogie Howser, M.D." from 1989 to 1993. On the small screen he's also starred in "Stark Raving Mad" and the CBS movie "The Wedding Dress" and done voiceovers for MTV's "Spider- Man." At the movies, where he debuted with Whoopi Goldberg in 1988's "Clara's Heart," he has worked with Madonna and Rupert Everett in "The Next Best Thing" and played the "token white guy" in "Undercover Brothers"; he just wrapped "Harold and Kumar Go to White Castle," due July 30. On Broadway, he played Anne Heche's suitor in "Proof" and the androgynous Emcee in "Cabaret." He returns Thursday to the venue of that latter role - Studio 54 - to portray the Balladeer and Lee Harvey Oswald in a riveting new production of Stephen Sondheim's musical "Assassins," directed by Joe Mantello. Harris, 30, ruminated with Newsday's John Habich recently in his dressing room about drama and politics - and a few days later cheerfully redid the interview by phone, thanks to a tape-recorder malfunction.

How did you start out in show business?

I went to a drama camp in northern New Mexico, where [playwright] Mark Medoff was an artist-in-residence. That led to a role in his film "Clara's Heart," which led to other roles, which led to the [TV] series. After I graduated from high school, I pondered college but just kept working. It seemed silly at the time to take off four years to take classes to learn to act. In hindsight, I don't know if that was the best decision. I love learning, and there's something great about a psychology or art history class taught by a brilliant professor.

To many people you will always be Doogie Howser. Is that a blessing or a burden?

If I say it's a curse, I will look incredibly ungrateful. If I say it's a blessing, I'd be lying. (He laughs raucously.) Look, "Doogie Howser, M.D." was incredibly well-written and gave me financial freedom I never would've imagined at 17 years old.

You've done a number of musicals in recent years. Does that represent a new career track?

I'm just interested in doing good material. I'm fortunate enough to have been working for long enough that the financial end is not a huge issue, so I'm able to choose material to which I'm responsive. That's especially important in theater. Otherwise, I don't want do something night after night after night.

What constitutes "good material" for you?

I follow intelligence and an interesting sense of humor, and confidence in the writing.

How do you think "Assassins" will resonate with audiences at this moment in U.S. history?

Since this is an election year, it's coming at a prime political time. The mudslinging has already begun so early. People have sort of a jaded view of way the political structure works in America right now; the nature of the presidency has been tarnished a little bit, which puts an audience in a little more political frame of mind. If the show were - knock on wood - to continue through the Republican convention, that would be incredible.

In what sense is it a political play?

It shows that all these people were not crazy. It's very easy in America today to label someone who does something heinous as crazy, whether it be Timothy McVeigh or Saddam Hussein. No one wants to sympathize with them; they've done something so horrible.

What's it like being in an ensemble cast instead of a traditional setup of stars, co-stars and bit players?

I expected more backstage conflict. I would just assume, in a show called "Assassins," that people vying for stage time would rub each other the wrong way, TV-style. But everybody gets their chance to shine. The cast is so supportive, across the board.

Tell us about "Charles and Kumar Go to White Castle."

It's by Danny Leiner, the guy who made "Dude, Where's My Car?" I play an actor named Neil Patrick Harris who's on ecstacy and desperate to go to a strip club, so I steal their car and leave them stranded.

So it's obviously autobiographical.

It couldn't be more like me. I was astonished; I thought they had bugged my apartment! I say this, of course, dripping with sarcasm.

You've worked in pretty much every medium. If you had to work in only one, which would it be and why?

Only one? (Long pause.) Live theater, because it's just more challenging, more legit. You're required to present to an audience that's never heard it, every single time.

With whom do you hang, when you have the chance to hang?

Mostly with the cast and a few people I know from other shows. I called a guy who was a tenor in "La Bohème," and his advice was, "Water and rest." I also work out at a gym with wide-screen TVs all over the place. At home I do the trapeze. A few years ago, a magician friend of mine started a trapeze class; you can go twice a week and swing for not much money. I'm working on my double back flip.