A stream of fresh revelations about Sarah Palin, the Republican vice-presidential candidate, continued to unnerve her party, including fiercely disputed allegations that she once belonged to a fringe Alaskan political party that wants independence from America.

A dozen Republican operatives and lawyers flew to the state to limit the fallout from what voters are learning about John McCain’s new running-mate — the day after her teenage daughter’s pregnancy was revealed.

It also emerged that in January the Alaskan Governor repeatedly laughed on air as a talk-radio host described one of her political opponents as a “cancer” and a “bitch”. The opponent in question, Lyda Green, the Alaskan state senate president, is a cancer survivor. An audio recording of the interview with Bob Lester, the Alaskan “shock jock”, had received more than a quarter of a million hits on YouTube by yesterday morning.

Meanwhile, officials of the Alaskan Independence Party — a fringe group that has been pushing for a referendum on whether Alaskans can secede from the US — said that Mrs Palin and her husband, Todd, were members in 1994 and even attended their convention that year. The party’s motto is “Alaska First — Alaska Always”. The McCain campaign produced voter registration documents that showed that Mrs Palin had registered in 1982 as a Republican and had never changed her party affiliation. They described claims of her membership of the AIP as smears.

Lynette Clark, the AIP chairman, said that the Palins were members between 1994 and 1996. “When she joined the [independence] party, our platform was right under her nose,” she said.

Republicans and Democrats said it was clear that Mrs Palin, 44, had not been vetted properly before being chosen last week by Mr McCain, who had met her only once. Yet the Republican nominee said: “The vetting process was completely thorough and I’m grateful for the results.”

Arthur Culvahouse, a veteran Wash-ington lawyer, who headed the vetting process, said that when she was interviewed, Mrs Palin volunteered information about her 17-year-old daughter Bristol’s pregnancy, and her husband’s 1986 drink-driving charge.

Details also emerged about the father of Bristol Palin’s child. He is Levi Johnston, 18, a high school ice hockey player. He describes himself on his MySpace page as a “f****** red-neck”. He says that he has a girlfriend but “I don’t want kids”. Last night Levi’s mother said that he was heading for the convention to meet the Palin family.

A central plank of Mr McCain’s campaign is his fight against federal, “pork barrel” spending on local pet projects. Mrs Palin said that she too was an antipork barrel crusader. Yet in Wa-silla, where she was mayor, she employed a lobbying firm that secured almost $27 million (£13.5 million) in federal funds for such items as a youth shelter and new railway line.

Democrat operatives said they were also turning their attention to her husband, Todd, a champion snowmobiler, to see what they could find out.

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