Sarah Palin will be formally nominated as the party's VP later this week
John McCain's US presidential campaign has angrily condemned the media for questioning the way his running mate Sarah Palin's candidacy was vetted.
Mrs Palin is preparing a key address to the Republican National Convention - days after she revealed that her unmarried daughter, 17, was pregnant.
Mr McCain's team denied claims it had not checked her background thoroughly.
Mr McCain is due to be nominated on Wednesday as the party's presidential candidate for the 4 November election.
Mrs Palin will make her key speech at the convention in St Paul, Minnesota, on Wednesday.
Ahead of the address, a written statement from senior campaign adviser Steve Schmidt said the "nonsense" over the vetting process for Mrs Palin should end.
"This vetting controversy is a faux media scandal designed to destroy the first female Republican nominee for vice president of the United States who has never been a part of the old boys' network that has come to dominate the news establishment of this country," the statement said.
Mr Schmidt said there would be "no further comment about our long and thorough process" in checking Mrs Palin.
The Alaska governor announced on Monday her 17-year-old daughter, Bristol, was pregnant, and would have the baby and marry her boyfriend.
It has also been revealed that an attorney has been hired to represent Mrs Palin in an Alaska state ethics investigation.
The case involves alleged abuse of power.
Mrs Palin is being investigated by state lawmakers over the dismissal of a state public safety commissioner, whom she allegedly sacked because he did not dismiss her brother-in-law, a state trooper, involved in a contentious divorce and child custody battle with her younger sister.
Sarah Palin told US network CNBC she had "nothing to hide". Her deposition is expected to be scheduled soon.
There have also been reports that Mrs Palin sought special financial favours for her city and state - something that the McCain campaign is against.
It has also been reported that her husband once belonged to a fringe political group in Alaska, with some members supporting secession from the United States.
Mrs Palin was elected governor of Alaska in 2006 and before that was mayor of the small town of Wasilla, Alaska.
She is due to be formally nominated by delegates as the party's vice-presidential choice later this week.
Sarah Palin's selection as vice-presidential nominee has caused great excitement among social conservatives and evangelical Christians gathered at the convention, says the BBC's Adam Brookes in St Paul.
But across the broader Republican Party, there seems to be some unease at the choice of someone who is an unknown quantity, he says.
Former New York Mayor Rudy Giuliani, who made a failed attempt to win the Republican nomination for president, defended her in a television interview for the CBS Early Show.
He said she had more experience than Democratic candidate Barack Obama.
"I would say Barack Obama has never governed a city, never governed a state, never governed an agency, never run a military unit, never run anything," he said.
The party's four-day convention opened on Monday, although it was initially curtailed because of the threat of Hurricane Gustav to states on the southern US coast.
On Tuesday, President George W Bush told delegates that Mr McCain was "a great American", describing him as a president ready to make tough decisions needed "in a dangerous world".
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