The surge of anger among US conservatives both with Barack Obama and the Republican party reached a new high point today when the Tea Party candidate, Christine O'Donnell, ousted the Republican establishment favourite in Delaware.

It was one of the unlikeliest outcomes of the primary season, given that even a few weeks ago O'Donnell was widely regarded as being so far to the right as to be unelectable.

The result delivers another shock to the Republican party establishment trying to withstand the battering it has had this year from the grassroots Tea Party.

O'Donnell, who is pro-gun, anti-abortion, fiscally conservative and believes masturbation is a sin, won by 53% to 47% for Mike Castle, who has served the Republicans for 30 years, including stints as governor and in Congress.

O'Donnell was the leader of the Christian lobby group Saviour's Alliance for Lifting the Truth. In a television interview a decade ago, she said: "The Bible says that lust in your heart is committing adultery. So you can't masturbate without lust."

She will now stand for the US Senate in November for the seat vacated by Joe Biden when he became vice-president two years ago.

Such is the anger among conservatives who think Obama is a socialist and the Republicans not rightwing enough that they were prepared to vote in O'Donnell, even though polls suggest she has little chance of beating the Democrats for the seat in November. The same polls suggested that Castle could win the traditionally Democratic state.

Her campaign received a boost two weeks ago when the Tea Party endorsed her and gave her $250,000 in funding. Last week she was given another boost when Tea Party favourite Sarah Palin also endorsed her as did the National Rifle Association.

Underlining just what a turnaround the result today was, O'Donnell only won about 2,000 votes in the Senate race in 2006. The national Republican party says it will not spend any money on O'Donnell, effectively throwing her under the bus. And Castle has already said he will not endorse her.

The night's real winner may yet be Democratic nominee Chris Coons, a formidable campaigner. He still has a hill to climb, but before last night's results it had looked to be a mountain. If the Republicans win eight senate seats in November, losing Delaware, they will dearly regret O'Donnell's primary victory.

Elsewhere, the New Hampshire Republican senate race was too close to call but Kelly Ayotte looked to be holding off Tea Party candidate Ovide Lamontagne. With neartly two-thirds of votes counted, it was 38% apiece. Whoever wins has a good chance of taking the seat, unlike in Delaware.

The high-profile, celeb-packed New York state attorney general Democratic nomination was being won by leftish candidate Eric Schneiderman (backed by Cynthia Nixon and Alec Baldwin) over Kathleen Rice (Mad Men's John Slattery) and Sean Coffey (Batman's Adam West).

In DC mayor's nomination, the reformist incumbent Adrian Fenty looked likely to be unseated by Vince Grey, an illustration of the perils of ignoring your base in a one-party town, especially in your first term. Grey attacked Fenty from the left, locked up union support and crushed him in the African-American vote.