Eclectic chanteuse Nellie McKay cannot be pigeonholed, or pushed around

Of all the performers to have emerged from Gotham in recent years, none epitomizes the burg’s dizzily paced eclecticism as vividly as Nellie McKay. Currently playing the featured role of Polly Peachum in the Broadway revival of “The Threepenny Opera,” the singer has forayed into pop, hip-hop and jazz, singing in Spanish, Japanese and Mandarin.

And while her lilting voice would seem to belie a personality that’s all sugar and spice, the twenty-something blond is perfectly capable of putting up a fight when pressed. McKay proved that late last year when she battled Sony, the label she was then signed to, over the contents of her sophomore album, “Pretty Little Head.” Execs wanted to trim her proposed double album by a third, which so enraged McKay that she took her fight to the stage, urging audiences to support her position through letters and phone calls.

The result? She’s no longer affiliated with the label and is currently having “Pretty Little Head” remastered — despite the fact that she’s not certain when (or if) it will ever see the light of day.

“Hopefully, it’ll come out sometime,” she says with a sigh. “I honestly have no idea. I just really believe it’s a better-balanced album as a longer album. I hope people get a chance to decide that.”

Balance is paramount to McKay, who expends just as much time and energy on local activism as she does on her career — a word she’d just as soon not use in referring to her artistic endeavors. She’s worked extensively on behalf of animal rights organizations, making newscasts by participating in protests about the poor treatment of Central Park’s carriage horses and penning songs like “Columbia Is Bleeding,” a scathing indictment of the animal experiments conducted by that New York institution’s medical school.

“I try to pick work that will allow me to somehow aid those causes,” she says. “Like in the program for (‘Threepenny Opera’), I mention vegetarianstarterkit.com, which is a really interesting site. I’ve been a vegetarian for 10 years, but it’s tricky, because food isn’t just sustenance, it’s a complicated relationship.”

Seated in her dressing room between Sunday performances of “Threepenny” — which runs through June 18 at Studio 54 — McKay proves that she doesn’t discriminate when it comes to her love for the critters. When a theater employee enters, offering to exterminate the roaches that have taken up residence there, she laughs off the offer.

“Oh no, they’re fine,” she demurs. “They go for sugar anyway, and all I have is salt. Cockroaches and coke — Studio 54 has always had huge problems with both.”

McKay wasn’t yet born during the disco mecca’s heyday, but says she probably wouldn’t have been a frequent visitor anyway. “I never really go out, to tell the truth,” admits the singer, who prefers simply strolling the streets around her shoebox Greenwich Village apartment. “That’s incredibly stimulating. It really encourages a lot of brain activity.”

The singer learned to navigate the Big Apple on the cheap early in life. Raised in Harlem by a single mom who bequeathed her a wide bohemian streak, her New York childhood wasn’t an Eloise-at-the-Plaza saga — but that doesn’t darken her appreciation for what she did have.

“I loved, absolutely loved the Italian restaurants,” she says with a wistful sigh. “I was always fascinated by the drawings on the tiles. When I go to one now, it still takes me back to when I was a kid. You know how they have signed photos on the wall of people like Ashley Judd or, back then, I dunno, David Letterman? We never went to chi-chi places, but that was really the essence of New York to me.”

As far as the city’s current essence? McKay’s not so sure. Spiritually, she lives in a bygone version of New York City, one where cafes and cabarets — not Starbucks and multiplexes — line the streets.

“It’s a totally different New York than when I was growing up, and that doesn’t make sense to me, because it doesn’t seem like there are that many more rich people in the world,” she says. “But all you have to do is be poor and it’ll be the same. I learned early on that the world is a very different place when you have nothing. You learn a lot when you don’t have extravagances to think about, and if you approach (the city) from that point of view, it’s a little easier.”

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