She has plenty to be outspoken about

WILL the real Nellie McKay please stand up? Or shut up, as the case may be?

The second option was requested loudly by a woman in the audience for McKay’s recent performance at the Troubadour. It came up while the singer was in the middle of an emotional rant about how corporations were raping us all and how her record company was threatening to release her new album in an unacceptably short version.

“This is important,” McKay shot back at the woman, who had suggested that she get back to singing. “If they put out the album that way then I’m going to quit music and I’ll never sing again!”

The epithet that finished off the comment got everybody’s attention.

McKay has shown a flair for doing just that ever since she arrived early last year, supplementing her musical appeal with an edgy persona. This was hardly the first time she’s flashed a confrontational side onstage. She’s become increasingly outspoken about animal rights and other causes, and now she’s taken her beef with Columbia Records to fans, urging her Troubadour audience to complain to the label and, for their convenience, spelling out the top man’s e-mail address.

She’s a handful, no doubt, but she might be worth the trouble.

McKay was just 19 when her first album, “Get Away From Me,” came out early last year, but her music was a panorama of multiera pop, big on show-tune brass and singer-songwriter confession, cabaret class and girl-group catchiness.

McKay’s lyrics skittered and danced atop her piano-led arrangements with precocious wit, evoking the wariness and anxiety that accompany the quest for contentment at a time of social and political uncertainty. “Yeah I’ll have my coffee black / Hey, look, we’re bombing Iraq,” goes her most widely cited couplet.

McKay quickly found her audience, earning comparisons to Randy Newman and a nomination for the connoisseurish Shortlist Music Prize. “Get Away From Me” finished No. 14 in the 2005 Village Voice critics poll and managed to sell pretty well, passing the 100,000 figure.

Now comes the new “Pretty Little Head,” due Jan. 3 at either 65 minutes (McKay’s version) or 48 (Columbia’s), bristling with more specific topical themes and a wider musical reach.

And she’ll stretch even more in April when she opens on Broadway in Wallace Shawn’s new adaptation of Brecht-Weill’s “The Threepenny Opera” with a cast that includes Alan Cumming and Edie Falco.

“She’s something to see,” says “Threepenny” director Scott Elliott. “I imagine at the end of the theater season everybody’s going to know her name. I think she can succeed at anything she wants to, because she has a lot of talent and she’s driven -- but in a way that feels good, not like crazy driven.”

Right now it’s not clear just what Nellie McKay (rhymes with “by”) wants to succeed at.

Onstage at the Troubadour, she looked like a woman living out her Doris Day dream -- robust, rosy-cheeked and ‘50s smart in her fuchsia jacket and billowing ponytail. But the McKay who walked into the empty club a few hours earlier, wearing a plaid shirt and black pants and carrying a turquoise leopard-print bag, suggested a shy street kid, her glance directed downward and her hair straight and uncombed.

Sitting in the shadows of her dimly lighted dressing room, McKay spoke softly as she talked about her career ambivalence. “I’m committed to animal rights. I’m committed to feminism,” she said. “I’m not committed to music at all. I don’t know where it’s gonna go. It’ll probably end badly.

“I guess you fall into whatever makes you feel best, and currently that’s music, but it could just as easily be something else.... I mean, when you see a movie about almost any profession -- it could be a dental hygienist -- it looks like that could be a nice life if it happened that way....”

Doing it her own way

McKAY’S casual view of her calling might not jibe with her intensity about the length of her new album, but it’s true that she’s not gearing up to sell it in conventional fashion. For one thing, her role in “The Threepenny Opera” means that she won’t be available to tour in the crucial months immediately after the release of her album.

“She doesn’t want to go on the road, she doesn’t want to perform, she doesn’t want to rehearse, she doesn’t even want to record,” said her manager, Robin Pappas, with a shrug, standing in the Troubadour showroom while McKay ran through a sound check with her band.

Occasionally Pappas hurried to the front of the stage and conferred with McKay about the music, gesturing to illustrate an emphasis in the beat. Then McKay would turn and talk to her four musicians, repeating the motions.

Pappas, a former actress, is also McKay’s mother, and they form an unusually tight-knit team as they spin on in their unconventional course through the singer’s idiosyncratic career.

In a way it’s a metaphorical continuation of McKay’s formative years, when she and her mother hit the highway in the late 1980s, traveling from New York to Olympia, Wash., and then back East. (Pappas split up with Nellie’s father, Scottish writer and director Malcolm McKay, when the girl was a baby.)

That was a formative experience for the youngster, a tough haul through a poor childhood that gave her a bond with the underdog and an antipathy toward the wealthy.

With her second album, McKay’s political concerns become even more prominent. “Pretty Little Head” includes songs about gay marriage, slain Harlem tenants’ rights activist Bruce Bailey and Columbia University’s primate laboratories. The song “The Down Low” is from a film musical McKay is writing with “Threepenny” director Elliott, based on Katherine Arnoldi’s graphic novel “The Amazing True Story of a Teenage Single Mom.”

McKay remembers reading about a song that once helped win freedom for a woman, Joann Little, who killed a prison guard who tried to rape her. And she cites Bob Dylan’s “Hurricane,” about imprisoned boxer Rubin “Hurricane” Carter.

“Eventually Hurricane Carter did get off,” she said. “I do think the publicity generated by the Bob Dylan song helped with that.

“Even if it doesn’t result in something specific, just drawing attention to it, say with ‘Hattie Carroll’ or ‘Brother Can You Spare a Dime,’ you’re a witness to the times you’re in, and that’s important.

“I want people to be able to sing along and enjoy it musically,” she added about the new album. “And if they find out about what Columbia University is doing and hear about Bruce Bailey and what a wonderful man he was before he was murdered -- there are various political important things in there, but I think it should stand musically. I hope it does.

“This album came out of so many projects, pieces or rejects from other projects. It’s interesting. It felt a lot more not about me. I like that.”

When it was time for McKay to get ready for the Troubadour show, even after talking about her aims and motivations, she had managed to remain a paradoxical and elusive figure.

“I don’t like being complex,” she said, sounding slightly stung by that observation. “I’d much rather things were simple. Take the Democrats. They aren’t simple. They’re very complex, and I hate them for it. I think war is very simple: Don’t do it, and the fact that no major candidate even approaches an antiwar platform disgusts me. And they all talk about how complex it is, and I think that’s bull.... I think it’s very simple.

“So no, I don’t really like being complex.”