If America wakes up on the morning of Wednesday 5 November to discover that John McCain has taken the White House and a moose-shooting former beauty queen from Alaska is now vice-president of the most powerful nation on Earth, there will be only one stronghold of the liberal elite that isn't reduced to outright mourning.

That will be the New York headquarters of NBC in midtown Manhattan, where a select handful of TV executives will be punching the air, re-examining their share options and celebrating the fact that their employee Tina Fey can carry on as the hottest property in US broadcasting for another four years.

Fey is a comedian, actress, and head writer for NBC's hit shows Saturday Night Live and 30 Rock, who won no fewer than three gongs at the recent Emmy Awards. More pertinently, she is responsible for the hugely funny impersonations of Sarah Palin that have propelled SNL to record ratings, become some of the most-watched video clips on the internet, and driven a fair portion of the agenda of the presidential election race in the process.

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Clad in thick spectacles and pastel-coloured jackets, and helped by their uncanny physical similarities, Fey and her merciless send-ups of the former beauty queen from Wasilla have done more to undermine Palin's campaign for the vice-presidency than the efforts of Barack Obama, Joe Biden, and the entire Democratic Party attack machine combined.

The outwardly-shy 38-year-old is now feted by the Washington press corps for providing a valuable satirical counterpoint to the Republican campaign, successfully deconstructing such central pivots of their ticket as Palin's claim that Alaska's physical proximity to Alaska makes her an expert on international affairs.

"Every morning when Alaskans wake up, they look outside and see if there are any Russians hanging around, and ask them what they are doing there," said Fey's version of Palin, in a hilarious send-up aired a fortnight ago. "And if they can't give a good enough reason, it's our responsibility to say 'Shoo!' and get them out of there."

Her sketches, which are now being quoted at dinner parties across the land, might explain why, in the words of USA Today, political commentators now believe that making voters forget the "Tina Fey Factor" provided Sarah Palin's chief challenge in the run-up to Thursday's vice-presidential debate.

The San Francisco Chronicle said the election could now turn on Palin's ability to make viewers forget the "cultural caricature", advising her in the debate to "acknowledge Fey's impression to help deflate its power". The Washington Post, for its part, noted sternly that some of Palin's recent gaffes have been so significant that Fey has taken to quoting her verbatim.

The Tina Fey phenomenon isn't just constrained to the political arena, though. In addition to her uncanny ability to satirise a politician who has a propensity to spout gobbledegook, she is currently helping to pioneer an important comic movement. To her fans, Fey is in the vanguard of a generation of sassy female performers who are now setting the agenda in US comedy. Together with her occasional collaborator Sarah Silverman, another edgy and sometimes potty-mouthed star, this makes Fey one of contemporary America's most alluring feminist heroes.

Her emergence in such lofty realms goes back to the critical and commercial success of 30 Rock, a sitcom she created and stars in, which won four awards at last month's Emmys, of which three went to Fey personally. When she stepped up on stage having achieved hat-trick of awards, she provided one of the evening's most memorable one-liners, saying that the trophy for Outstanding Comedy Series "actually belongs to everyone, so I don't like it as much as the other two".

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The programme is set in the offices of a television company similar to NBC, and debuted exactly two years ago. It is said to have been inspired Fey's real-life experiences behind the scenes of Saturday Night Live, which she joined as a writer in 1997.

Its title is a corruption of NBC's head office address, 30 Rockefeller Plaza. Fey plays a neurotic head writer at the network who is constantly forced to sacrifice her artistic credibility to navigate between her hopeless co-writers and right-wing boss, who is played by Alec Baldwin, in a role that has reinvigorated his career. The success has allowed Fey to start making waves as a film actress. Her debut film Baby Mama made more than $63m, and she is scheduled to return to the big screen next year in a new Ricky Gervais title, This Side of Truth.

The irony of Fey's recent rise has been that the lion's share of her original success came behind, rather than in front of camera. Born in 1970 and brought up in middle-class Pennsylvania, her route into showbusiness came via Second City, a small but well-regarded improvisational theatre in Chicago, where she took evening classes in the early 1990s, after graduating from the University of Virginia with a degree in drama.

"I had a vague notion Second City was there in Chicago, and I just wanted to be near it, to see what I could do," she recalled, during an interview with The Washington Post in 2004. "This is where I met all my dearest friends in my life now. I met them all at that time." Among those "dearest friends" was Fey's future husband, composer Jeff Richmond, whom she married in a Greek Orthodox ceremony (a nod to her mother's ancestry), and with whom she now has a three-year-old daughter, Alice. The couple moved to New York in 1997, so Fey could make her debut as a writer for Saturday Night Live.

Within two years, she had been promoted to head writer, the first female to take the role in the show's 33-year history, which at the time was considered a signal appointment. The programme's producer, Lorne Michaels explained her rise by complimenting her ability to "get things done", and saying her jokes were distinguished by "intelligence and attack, an attitude. There's something for you to enjoy after you've finished laughing".

Michaels was also a central figure in Fey's next leap, to become a major screen personality. Having seen her perform a sketch she'd created with Saturday Night Live colleague Rachel Dratch at a New York theatre, he persuaded her to audition for the presenter's role in the "Weekend Update" segment of the show. When Fey made her debut in the slot in late 2000, she began to gain a following. Viewers loved her spectacles and her prim demeanour, and became fascinated by the scar on her left cheek – about which she once told The New York Times: "It's a childhood injury that was kind of grim. And it kind of bums my parents out for me to talk about it."

The Washington Post started describing her as an "anchor minx", while gossip magazines dubbed her a TV "hottie". (She claims to have kept the cuttings to show to her children.) Soon she had become a minor sex symbol of late-night TV. "There's a group of people who feel Tina can do no wrong in my eyes," Michaels has said. "But that's because she's just wrong less often than other people."

Now, though, Fey has achieved mainstream success, thanks both to the growing critical acclaim showered on 30 Rock and universal appeal of her Sarah Palin impersonation, which perfectly mimics the Alaska governor's yokelish accent, and perfectly replicates her propensity to wink uneasily yet vaguely seductively at the camera when she lands in a tight sport.

Although it's a job that NBC would be happy to have her doing for some time, Fey – one of the many Hollywood liberals hoping for a Barack Obama victory – has selflessly claimed that she hopes to put an end to the potentially lucrative role. "I want to be done playing this lady by 5 November," she said backstage at the Nokia Theatre after the Emmy Awards. "So if anybody can help me be done playing this lady, that would be good for me."

A life in brief

Born: 18 May 1970, in Pennsylvania.



Early life: Grew up outside Philadelphia with her parents, a paramedic and a housewife, and one brother. A lover of comedy from an early age, she found she could amuse her friends at school. Studied drama at the University of Virginia, graduated in 1992 and moved to Chicago where she started working and taking classes at the Second City improv club.



Career: In 1995 she was discovered at Second City by 'Saturday Night Live', eventually becoming the first female head writer in the show's history. In 2004 she wrote the hit film 'Mean Girls', starring Lindsay Lohan, and she gave up the 'SNL' head writer job in 2005. She now writes and stars in NBC's Emmy-winning series '30 Rock'.



Family: Married to Jeff Richmond, a director at Second City. They have a daughter, Alice Zenobia Richmond, born on 10 September 2005. All three live in New York City.



She says: "Somewhere around the fifth or seventh grade I figured out that I could ingratiate myself to people by making them laugh. Essentially, I was just trying to make them like me. But after a while it became part of my identity."



They say: "Tina has a gift of knowing how to push things as far as she can and still be on a network." Alec Baldwin, star of '30 Rock'