Sarah Palin touted her small-town roots and took a swipe at Democrat Barack Obama during her speech to the Republican convention on Wednesday, ridiculing her critics as out-of-touch elitists who do not understand everyday life in America.
Her debut speech came just five days after John McCain shocked the US political world by introducing the first-term governor as his running mate in the election against Senator Obama and his No 2, Delaware Senator Joe Biden on 4 November.
Ms Palin gave a fiery defence of her position outside what she called the Washington elite, and said she would go to the capital not to seek the good opinion of commentators, but to serve the people.
The first woman vice-presidential nominee for the Republicans drew roaring cheers from supporters when she came out swinging against the Democratic nominee and members of the news media who have questioned her qualifications.
"I've learned quickly these past few days that if you're not a member in good standing of the Washington elite, then some in the media consider a candidate unqualified for that reason alone," the Alaska governor told the crowd.
Defending her small-town roots, she attacked Mr Obama as having talked of change but done nothing of substance. She praised the "determination, resolve and sheer guts" of Mr McCain and said she was honoured to help him.
Mr McCain was formally nominated as the Republican presidential candidate on Thursday.
Mrs Palin gave her much-anticipated address to a packed and enthusiastic convention floor in St Paul, Minnesota. She spoke of her family, including her eldest son, who is about to be deployed to Iraq in the Unitd States Army, and her youngest son, who has Down's Syndrome.
The mother-of-five highlighted her background as a small-town "average hockey mom" and stressed the fact that she is not part of the "Washington elite".
She also attacked Mr Obama's "change agenda" and suggested he was more interested in idealism and "high-flown speech-making" than acting for "real Americans".
"In politics, there are some candidates who use change to promote their careers. And then there are those, like John McCain, who use their careers to promote change."
Since Mr McCain made the virtually unknown Ms Palin, 44, his choice for running mate, she has been the center of a media storm fueled by disclosures about her unmarried teenage daughter Bristol's pregnancy, a probe into her role in an Alaskan official's firing and questions about her political record.
Her anti-abortion and pro-gun history has excited conservatives and party activists, but her convention speech gave Americans their first chance to judge her for themselves.
Ms Palin said her service as a mayor and a town council member in Wasilla, Alaska, had given her a realistic perspective.
"When I ran for city council, I didn't need focus groups and voter profiles because I knew those voters, and knew their families, too."
She contrasted that with Mr Obama's background as a community organiser in Chicago and a first-term senator from Illinois.
"Before I became governor of the great state of Alaska, I was mayor of my hometown. And since our opponents in this presidential election seem to look down on that experience, let me explain to them what the job involves," she said.
"I guess a small-town mayor is sort of like a 'community organiser,' except that you have actual responsibilities."
The furor over Ms Palin has raised questions about Mr McCain's judgment and the depth of the investigation that preceded her selection.
Mr Obama told voters in Ohio that the Republicans had barely mentioned the faltering United States economy at their convention session on Tuesday. Opinion polls show voters rank the economy as the top election issue.