US Republican presidential hopeful John McCain has picked Sarah Palin, the female governor of Alaska, as his surprise running mate.
At 44, she is younger than Barack Obama and is credited with reforms during her first term, but she is relatively unknown in US politics.
Mr McCain has gone on stage at a rally in Dayton, Ohio, to celebrate his 72nd birthday and present Ms Palin.
Analysts say the Republican is keen to wrest back headlines from Mr Obama.
The youngest governor of Alaska and the first woman to hold that position, Ms Palin is married with five children.
Ms Palin is perhaps the most daring vice-presidential choice for Mr McCain, the BBC's Kim Ghattas reports from Dayton.
Todd and Hillary
Speaking to a large crowd, who sang Happy Birthday when he appeared, Mr McCain introduced Ms Palin as someone who "understands working people".
"She's got the grit, the integrity and commitment to the common good which are exactly what we need in Washington today," he said.
"She's exactly who I need, who this country needs, to help me fight to turn the same old Washington politics on its head."
Thanking Mr McCain, Ms Palin said she would be honoured to serve next to him.
She introduced her family including her husband of 20 years, Todd, saying:
"My husband was a lifelong commercial fisherman... [He is now] a production operator up in the oil fields up on Alaska's north slope, and he's a proud member of the United Steelworkers' Union. And he's a world champion snow machine racer."
Speaking of her time in office in Alaska, she said she had "fought corruption".
She paid tribute to other American women in politics, including Hillary Clinton, Barack Obama's defeated Democratic rival:
"It was rightly noted in Denver last week that Hillary left 18 million cracks in the highest, hardest glass ceiling in America. But it turns out the women of America aren't finished yet and we can shatter that glass ceiling once and for all."
The Obama campaign suggested Mr McCain's choice was irresponsible, referring to Ms Palin's former role as mayor of the small Alaskan town of Wasilla.
"Today, John McCain put the former mayor of a town of 9,000 with zero foreign policy experience a heartbeat away from the presidency," said spokesman Bill Burton.
Broad appeal
Ms Palin may reinforce Mr McCain’s "maverick" tag, enjoying a reputation as someone willing to take on the party establishment.
Analysts say she may have been chosen by the McCain campaign as a tactic to win over Democratic women voters, disappointed by the defeat of Hillary Clinton to Barack Obama.
Her relative youth and reforms as governor may also go some way to match Mr Obama's appeal, and boost Mr McCain's chances.
"She will be his partner in reforming Washington," a senior McCain official told Reuters news agency, speaking on condition of anonymity.
Announcing Mr McCain's decision, his election website said Ms Palin had "brought Republicans and Democrats together within her administration [in Alaska] and has a record of delivering on the change and reform that we need in Washington".
At the same time, Ms Palin is a strong conservative, fiscally and socially.
She also opposes abortion and her baby son has Down's Syndrome.
Abortion has been a key issue cited by Republican voters who feel the Arizona senator is not conservative enough, our correspondent says.
Alaskan investigation
Ms Palin lacks foreign policy experience and while being a Washington outsider can be an asset for the McCain ticket, it also means she has not been tested on the national stage, our correspondent says.
Her electoral chances may be harmed by the fact that she was placed under investigation in Alaska by state lawmakers at the end of July.
She sacked a public safety commissioner and the allegation is that she sacked him because he had not fired a state trooper who is Ms Palin’s former brother-in-law, and who is in a custody battle with her sister.
She says she has "nothing to hide" and is "cool" about the investigation.
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* Elected Alaska’s youngest and first woman governor in 2006
* Grew up in Wasilla, near Anchorage, and was voted Miss Wasilla in 1984
* Studied journalism and political science at University of Idaho
* Is mother of five, including a son with Down's syndrome
* Her husband Todd is an oil production operator
* Likes hunting and fishing
i thought corporate america had got rid of them trouble makers ages ago 
union and america in the same sentence? it blows my mind! 
