WHO'S NEW? ESTABLISHED TV DRAMAS JUGGLE CASTS AND HOPE AUDIENCES STAY WITH THEM.

Byline: Valerie Kuklenski Staff Writer

THERE WAS a time when a lead actor needing a way out of a TV series would have given writer-producer Rene Balcer a serious case of stress.

Not any more. As a writer on ``Law & Order'' for its first 10 years and the show-runner for four, he had seen plenty of people come and go at the New York police precinct and prosecutors' offices that are the setting of the NBC series.

So it was not such a big deal when it became obvious that Vincent D'Onofrio needed to lighten his duties at ``Law & Order: Criminal Intent,'' the spinoff series Balcer now runs as executive producer.

``We just realized the workload was so insane that we had to come up with a solution in order to keep Vincent on without killing him,'' Balcer said matter-of-factly. Hourlong episodic television has a reputation as the most brutally demanding work for actors on camera.

``So we came up with this notion - it's not a new notion - of having alternating partners from week to week,'' Balcer said. Next fall, D'Onofrio and Kathryn Erbe will co-star in half the episodes, while ``Law & Order'' alum Christopher Noth revives his Detective Mike Logan character in the remaining episodes, opposite a woman partner whose casting has not been announced.

It's just one of many cast shuffles viewers will notice in network dramas. ``Sopranos'' regular Michael Imperioli has stepped into ``Law & Order'' as a detective so that Jesse L. Martin could take a few weeks off to film the musical ``Rent.'' Noah Wyle will be leaving ``ER'' soon.

And then there's ``The West Wing,'' which could undergo an extreme series makeover in the coming season as lame duck Josiah Bartlet (Martin Sheen) turns over the Oval Office to a new presidential administration. Front-runners for ``West Wing'' stardom are Alan Alda as Republican Sen. Arnold Vinick and Jimmy Smits as Democratic Rep. Matt Santos.

Robert Thompson, director of Syracuse University's Center for the Study of Popular Television, sees turnover among actors as a good thing for both viewers and series writers.

``With a single set of characters, in time you run out of things to do with them,'' Thompson said. ``By the time we got to the end of 'Friends,' there was nothing to do with it. We had seen all the permutations.''

He said switching out characters ``puts some new narrative DNA into the mix.''

Balcer recalled the anxiety he and ``L&O'' creator Dick Wolf experienced when George Dzundza asked to be written out so he could spend more time with his family. His detective character was killed off at the end of the first season.

``The first two or three seasons, that's when the show is precarious anyway. It doesn't matter what show you're on,'' he said. ``So any major change caused a lot of trepidation. We didn't know how the audience was going to take it. It could have been a potentially fatal blow, especially since he was in the first half of the show, and that's when people tune in.''

But ``Law & Order'' withstood the departure of Dzundza, Michael Moriarty and virtually everyone else on camera. In the fall of 2000, the series had a completely different core cast from the one it began with 10 years earlier.

Bob Gustafson, director of the Entertainment Industry Institute at California State University, Northridge, says a series' structure is key to weathering cast changes.

``I think if the world of the show - the setting and the tone and the feel - if that's interesting and compelling, the residents in that world can change, and (viewers) will come back,'' he said. ``If that world is not compelling, more than the characters in it, it won't last.''

Imperioli says viewers' sticking with a series through its cast changes is a testament to the quality of the writing. He thinks dramas lend themselves to such transitions more easily than comedy series.

``Sitcoms aren't as story-driven as they are by a specific type of humor that comes from a character, whereas especially in these crime dramas, they're really more story-driven shows,'' Imperioli said. ``So as long as the stories are interesting and you get good actors, I think people are going to be willing to try it.''

Putting new faces on established shows became easier with the advent of big ensemble productions in the early '80s. ``Hill Street Blues'' and ``St. Elsewhere'' went through it, and the list of players on ``Dynasty'' is as long as Aaron Spelling's arm.

But in the age of network audience erosion and channel-surfing, series are desperate to hold on to their shares of viewers - particularly those on NBC, which has seen sharp ratings declines this year. It's a judgment call whether stability or change brings about that end.

Odds are in favor of a Smits presidency on ``The West Wing.'' Alda would be 70 in the fall of 2006, when the new administration settles in. And he's a New Yorker, while the show films in Burbank. Also, John Spencer's chief of staff character, Leo McGarry, was tapped in the season finale to be Santos' running mate, increasing the likelihood that other supporting players would stay on if Smits wins.

It also would seem obvious to placate its mainly Democratic audience with another Democrat in power. A recent Zogby poll of ``West Wing'' viewers showed Smits beating Alda, 44 percent to 28 percent.

``Well, I'm very flattered by that, and Zogby is very respected, as we all know,'' Smits said. ``But considering the effect that polls had on the 2000 election and the more recent election, I can only put so much credence in the polls.''

A politically active Democrat who spoke at his party's national convention in 2000, Smits says he is gaining insight about the way things work inside the Washington Beltway, as well as a little perspective.

``I like the fact that this season we're hearing on the show strong voices on both sides of the aisle. I think it's a good move that (executive producer John Wells) made to have a character (played by) an actor who is as appealing as Alan Alda that gives that strong Republican voice.''

TV expert Thompson says shaking the show up with an Alda victory would be a good idea - if a very dangerous one.

``There are no slouch characters (in the current ensemble). They've taken home a bevy of Emmy Awards, and there's a big fan base for those people.

``But I think it's done what it could do. It's had some memorable stories, (but) it needs to pull a 'Law & Order' now. And they've got a perfect excuse to do it because they've got it built into the narrative.''

Balcer says all types of shows - legal dramas, police procedurals, hospital series - can succeed with new players.

`` 'Lost' - you could kill off half your cast and no one would really notice,'' he said. ``And 'Desperate Housewives' - I mean, you can't even get them to do a photo shoot together without clawing each other's eyes out, so who knows who could move in and out of a neighborhood?''

Balcer points out that even the 1960s sitcom ``Bewitched'' survived a big personnel change.

``Look, ever since they changed a Darrin (Dick York) for a Darrin (Dick Sargent), people will accept a cast change.''

Valerie Kuklenski, [phone]

valerie.kuklenski(at)dailynews.com

Who's out, who's in

You can't tell the drama series players without a scorecard these days. Here's a rundown on who's coming and who's going from network shows, all on ratings-challenged NBC:

``Law & Order'' (season finale May 18)

Out: Jesse L. Martin as Detective Ed Green. His character was seriously wounded in the April 13 episode, giving Martin a short-term out to film scenes for the movie musical ``Rent.''

In: Michael Imperioli (``The Sopranos'') as Detective Nick Falco, a temporary transfer from a tougher precinct. He's in a total of four episodes through the season finale. Previously played a guest-star bad guy in a 1996 episode.

``Law & Order: Criminal Intent'' (season finale May 22)

Out: Vincent D'Onofrio and, in a guilt-by-association move, Kathryn Erbe in half the episodes beginning next fall. D'Onofrio, who plays Detective Robert Goren, needed a lighter workload.

In: Christopher Noth as his old ``Law & Order'' character, Detective Mike Logan, plus a woman partner to be named later. Noth already had been booked for a guest role when the need to replace D'Onofrio arose, and show runner Rene Balcer says he liked Logan's ``fish out of water'' fit in the elite squad.

``ER'' (season finale May 19)

Out: Noah Wyle, the last original core cast member, give or take the Sherry Stringfield factor. His Dr. John Carter will reunite with his lover, Kem (Thandie Newton), in Paris and return to County General in Chicago for a farewell. The season finale on May 19 marks the end of his stint as a regular, although he will make a handful of guest appearances next season.

In: To be announced. The male lead hat is more likely to be passed to an established star such as Goran Visnjic or Mekhi Phifer than a series newcomer.

``The West Wing'' (season complete)

Out: By the end of next season, Martin Sheen's Josiah Bartlet and some or most of the rest of the cast, depending on the outcome of the series' presidential election.

In: Next season, both Alan Alda as Sen. Arnold Vinick and Jimmy Smits as Rep. Matt Santos as contenders for Bartlet's job. If Smits' character wins, supporting players such as John Spencer (as Leo McGarry) and Allison Janney (as C.J. Cregg) are likely to remain. If the Republican played by Alda wins, expect a near top-to-bottom cast change.

- V.K.

CAPTION(S):

5 photos, box

Photo:

(1 -- 2 -- cover -- color) SOMETHING OLD

SOMETHING NEW

TV shows reinvent themselves with cast changes

(3 -- 4) Cast changes are more the rule than the exception on ``Law & Order'' and its spinoffs, with ``Law & Order: Criminal Intent'' adding Chris Noth (top right, with Vincent D'Onofrio and Kathryn Erbe) and the original ``L&O'' bringing in Michael Imperioli (above left, with S. Epatha Merkerson and Dennis Farina).

(5) One of these two actors - Jimmy Smits, left, and Alan Alda, right - will become president on ``The West Wing.'' (Karis Campbell, center is an aide to Smits' Rep. Matt Santos character.)

Box:

Who's out, who's in (see text)