In Delaware, Republican voters shoot themselves in the foot by nominating tea party Senate candidate Christine O'Donnell who can't and won't win in November. This dims Republican hopes of winning back the Senate. Elsewhere tea party candidates who have challenged and beaten Republican establishment candidates like in Alaska, Kentucky etc. will probably win their races.

O'Donnell defeated former governor Mike Castle in an ugly race.

Castle is a liberal Republican but a political moderate. O'Donnell is basically as conservative as a political candidate can get. Delaware has elected moderate Repubicans and liberal Democrats but it has never elected an ultra conservative before. Even in this year of public disgust with how Democrats have been running things in Washington, it won't this November.

UDATE: Bill Kristol opines:

Tea Party activism, enthusiasm and, yes, rebelliousness have been, on net, a very good thing for the GOP. Now in politics as in life, there can be, on occasions, too much of a good thing. Thus Delaware. But it's still much, much better to be the party to which independents and new voters are flocking, and in which activists are energized, than not. And it's better for the GOP, as the out party, that the anti-establishment and anti-incumbent wave is still building (which it clearly is) rather than ebbing. A year ago, the liberal media hoped tea partiers were going to generate suicidal third-party challenges, scare off independents from the Republicans, and generally destroy the Republican party. It turns out they've probably cost the GOP one Senate seat on the way to a huge off-year election victory. It's a small price to pay.