Who is Christine O'Donnell?

After setting out to destroy him, Christine O'Donnell is one of a handful of Republicans who probably saved Barack Obama from complete humiliation in the 2010 mid-term elections.

Miss O'Donnell, 41, rode last year's Tea Party wave to win the Republican nomination for the US Senate seat in Delaware vacated by Joe Biden when he became Vice-President.

She inflicted a shock defeat on Mike Castle, the mainstream Republican candidate, who had served nine terms in the US House of Representatives after being governor of the state.

But in the general election, she turned a race that had looked winnable to many Republicans into a thumping victory for her Democratic opponent, Chris Coons, who won by 57 per cent to 40 per cent.

The defeat, blamed by some on her Right-wing positions on social issues alienating independent voters, also came at the end of a campaign that lurched from one public relations disaster to the next.

Bill Maher, a Left-wing television host, dug out footage of Miss O'Donnell on his show in 1999 saying that she had "dabbled into witchcraft". The remark received widespread media attention.