After wrapping up his last season of "Law & Order: Criminal Intent," as well as the blockbuster "Sex and the City" movie, Noth was busy renovating a house in California for his now 9-month-old son, Orion, whose mother is Noth's longtime girlfriend Tara Wilson.

"Then you read the play and you're always astonished when someone is interested in you for something that's really exceptionally well written," Noth said during a laid back interview at the swanky Gotham Bar and Grill. "They really want me? It's good?"

But Noth, who has the disarming habit of punctuating his self-deprecating comments with a boisterous laugh, was less than self-assured about returning to the stage.

That comes as a surprise to those _ including his co-star, John Gallagher Jr. _ who expect Noth to share the swagger of his famous TV characters Mr. Big or Detective Mike Logan. "I had this notion of him as being this truly tough guy, and I'm sure that exists inside of him, but in truth he couldn't be sweeter," Gallagher said.

Beau Willimon's timely play follows the top campaign staff of a Democratic candidate for president in the frantic last days before the key Iowa caucuses. Noth stars as Paul Zara, the campaign manager. Gallagher, who won a Tony Award for his performance in "Spring Awakening," stars as the campaign's brilliant young press secretary, who is tempted to trade his values for personal ambition.

To prepare for the role, Noth talked politics over dinner and drinks with Joe Trippi, a veteran political operative who managed Howard Dean's bid for president, among other campaigns.

"The sacrifices that these guys make and what they put themselves through is astonishing," Noth said. "I mean, they literally make themselves ill with the stress and the life on the road _ it's something I hadn't quite realized."

Director Doug Hughes said he was introduced to Noth as a stage actor through his Broadway performance in another political drama _ the 2000 revival of Gore Vidal's "The Best Man."

"I think that this character has a kind of fearless vulgarity to him," Hughes said of Paul Zara. "And I think Chris has the guts to fully bring into focus the character's flaws and foibles and frailties."

The strength of the script brought Noth back to New York City and the intimate Linda Gross Theater, where the play will run through Nov. 29.

"It's a very homey theater away from Times Square," Gallagher said. "We actually all share a dressing room with a curtain down the middle."

The intimacy suits Noth, who said he prefers the camaraderie of a theater ensemble to the spotlight.

Noth had praise for the entire cast, which also includes Isiah Whitlock Jr. of HBO's "The Wire" and Olivia Thirlby, who starred in "The Wackness" and "Juno."

He credits Hughes for helping him through his own rough patches. He said returning to theater came as a greater challenge after the rhythms of a procedural drama such as "Law & Order," which he left this summer after three seasons. (He played Logan on the original series from 1990-95 and starred in a "Law & Order" TV movie, "Exiled," in 1998.)

"I think we had some good writers and I think we did some great shows so I don't want to sound cynical," Noth said, "but in general, that kind of TV runs on its own impetus. It doesn't require great subtlety of acting or any kind of requirement beyond driving the plot forward so people get the reversals in the story."

Noth expressed a complicated mix of frustration and appreciation toward Dick Wolf's "Law & Order" empire, with its spin-offs and rotating casts. He thinks the series is ultimately more focused on profit than art.

"I think that can make you cynical as an actor and I think it can make you feel like acting doesn't matter and I think it does matter," he said. "I think it is a noble art and theater makes you realize that."

Noth's acting career began onstage as a student at Marlboro College in Vermont, where he emulated Henry David Thoreau by building a shack in the woods where he would go to write. "A real idiot," he said wryly about his undergraduate pretensions. After graduation, Noth studied privately with Sanford Meisner in New York before attending the Yale School of Drama in New Haven, Conn.

While Noth's career took off after joining "Law & Order," his life changed forever after appearing in HBO's "Sex and the City" as the impossibly cool, unattainable Mr. Big. The show's popularity skyrocketed at a moment when new technology, such as blogs and digital cameras, was opening up the lives of celebrities to public exposure like never before.

He cites the explosion of camera phones as a key development. "That changed the whole game," he said. "Because not everybody walked around with a camera. Now everybody does." Noth, who enjoyed riding his bike on the streets of Manhattan and taking public transportation, suddenly couldn't leave his apartment without becoming a photo opportunity.

Noth acknowledges some discomfort with the attention, but said he's getting better about handling his celebrity and the accompanying kudos, which have included a Golden Globe nomination.

He credits the writing of Michael Patrick King for his success in the Mr. Big role, as well as Sarah Jessica Parker, who turned the quirky Carrie Bradshaw into an icon. "I'd often say to her, 'I'm just riding your coattails, baby. Whatever you're doing, let me know, I'm there!" Noth said with his boisterous laugh.

Noth will return to big-screen romantic comedy next year, starring in "My One and Only" with Renee Zellweger. With "Apocalypse Now" scribe John Milius as a partner, Noth is also hoping to produce a limited TV series for AMC called "Saigon Bureau" about combat photojournalists who died in Vietnam. He has been working on the project since 2001, after stumbling into a museum in Saigon where photos of Sean Flynn, Larry Burrows and other photographers were on display. He has been "obsessed" with their work ever since.

As for stage, Noth said "Farragut North" was exactly what he needed to "shake the rust off," as he put it. "I'm feeling the hunger again and I feel a bit more confidence about myself as a stage actor starting to come back after ... feeling like Sisyphus rolling a stone up and seeing it roll back down."

His first priority, he said, is to resist becoming complacent. Borrowing from one of his favorite poets, Robert Frost, he added, "I've got miles to go before I sleep as an actor."