A dream night for the Tea Party – a nightmare for the Republicans

Far-right's strong showing in primaries raises prospect that Democrats could keep control of Senate in mid-term elections

A Tea Party-backed candidate in Delaware who built her public career advocating sexual abstinence has snatched the Republican nomination to run for the US Senate seat in November, stunning the party establishment.

The upset victory by Christine O'Donnell, 41, in the Delaware primary contests serves to confirm a reality that has been creeping up on the Republican leadership for months: as it tries to train its guns on Democrats in time for the midterm elections in November it is also facing a powerful right-wing insurgency from within its own ranks.

Ms O'Donnell, a marketing consultant, won even though she had been lambasted by others in the Republican Party – the local party chairman described her as "as a delusional liar". Her victory illustrates the truculent national mood and the unwillingness of voters to listen to their party leaders.

The lessons were similar elsewhere on Tuesday, which saw the last big round of primaries before the November midterms. The once very popular Washington DC Mayor Adrian Fenty, a Democrat, lost his primary race. Republicans in New York were dumbfounded as their party-supported candidate for governor, Rick Lazio, went down to the much more conservative Carl Paladino, who has vowed to take a "baseball bat" to the state capital.

Mr Paladino's fortunes were apparently not dented by the release of emails he had sent to friends with racist jokes and pornographic images – one actually showed a digitally-doctored image of President Barack Obama and Mrs Obama as a pimp and prostitute. The national consequences of his win may be limited, however. Few would have expected even Mr Lazio to beat the Democrat candidate for the governorship, Andrew Cuomo; Mr Paladino's chances seem still slimmer.

The fallout from Ms O'Donnell's win is more easily guessed at. Republican leaders had been counting on a win on Tuesday by her rival Mike Castle, a moderate in the party who has held state-wide elected positions in Delaware for roughly four decades. It was assumed not only that he would win the primary but thereafter he would go on to win the Senate seat that once belonged to the Vice President, Joe Biden.

That assumption does not hold for Ms O'Donnell. It is not even clear that the Republican Party in Washington will funnel funding to her campaign amid assessments she cannot win in November because her views are too extreme to attract all-important independents. More disastrously, not taking the Delaware Senate seat might put the cherished goal of taking control of the US Senate out of the party's reach.

Party unity in the wake of Ms O'Donnell's win will also fray. Karl Rove, the Republican commentator and former Bush aide, expressed his dismay to Fox News. "There's just a lot of nutty things she's been saying that just simply don't add up," he said. "I'm for the Republican, but I've got to tell you, we were looking at eight to nine seats in the Senate. We're now looking at seven to eight. In my opinion, this is not a race we're going to be able to win."

Ms O'Donnell appeared unconcerned at party leaders' discomfort. "I didn't count on the establishment to win the primary," she said on ABC's Good Morning America. "I'm not counting on them to win the general. I'm counting on the voters of Delaware."

It was the third time that Ms O'Donnell had made a run for the Senate in Delaware and earlier this season she was being dismissed by the party and by the media as little more than a gadfly who never gives up. Yet she gained traction. Help came in part with high-profile endorsements from the two most popular figureheads of the resurgent right, Senator Jim DeMint of South Carolina and Alaska's Sarah Palin.

As she noted herself on Tuesday night, she seems also to have bottled a particular energy from women voters, who may be angry not just at the establishment but also at the "white guys" who populate it. In one TV interview, she spoke lavishly of the US Secretary of State, Hillary Clinton, for "blazing the trail" for women in American politics.

The storming of the Republican bastion began in May when a rowdy state Republican convention ditched the incumbent Senator Robert Bennett in favour of a Tea Party-backed rival. Then in Kentucky the candidate backed by the Senate Minority Leader Mitch McConnell was trampled by Rand Paul. He is a Tea Party favourite, as is Sharron Angle, who won her primary to take on the Senate Majority Leader, Harry Reid, in Nevada.

Altogether eight establishment-backed Republican candidates have been ousted in this year's primary process by more conservative rivals. It is a pattern that has highlighted the influence of the Tea Party movement – ragtag and unstructured as it may be – and injected serious complications into the strategy of the Republican Party in a year when taking advantage of the unpopularity of Democrats should have been straightforward.

The winners: Outsiders now on the inside track to power

Christine O'Donnell

Age 41

Experience On her third bid for the Senate, after losing to Democrat Joe Biden in 2008 and finishing last in a Republican Senate primary in 2006.

Cost of campaign Initially campaigned on a shoestring, but later received up to $250,000 from a Tea Party organisation.

Policies Anti-abortion, anti-health care reform and supports abstinence-only sex education. Backs limited government and free markets.

Why she's a controversial pick She has reportedly struggled with personal debt and claimed that her political opponents hide in her bushes. She condemned masturbation as adulterous, saying: "The Bible says that lust in your heart is committing adultery."

What she says "This is about giving the political power back to we, the people, and we proved the so-called experts wrong."

What they say "There's just a lot of nutty things she's been saying that just simply don't add up." – Karl Rove, veteran Republican strategist

Carl Paladino

Age 64

Experience First bid. His website says: "Carl Paladino is not a politician."

Cost of campaign $3m from personal funds.

Policies To slash taxes and state-funded healthcare programmes. He has vowed to stop the ground zero mosque project.

Why he's a controversial choice Paladin has a penchant for forwarding offensive emails. These have included images of the Obamas doctored to look like a pimp and a prostitute.

What he says "We are mad as hell. New Yorkers are fed up. Tonight the ruling class knows."

What they say "Paladino purports to be the values candidate, but what will values voters say when they discover that he enjoys sending hardcore pornographic and racist emails around town?" – WNYMedia.net, the blog that published the controversial emails