Christine O'Donnell, Tea Party Favorite, Stuns Mike Castle in Delaware

Christine O'Donnell, an insurgent Tea Party candidate and Sarah Palin protege, stunned nine-term Rep. Mike Castle and the Republican Party establishment Tuesday night when she trounced the former two-term governor, 53 percent to 47 percent. Not only is the Delaware Senate seat seen as crucial for control of the Senate, it is also the seat formerly occupied by Vice President Joe Biden.

Castle addressed his supporters moments after the results came in. "The voters in the Republican primary have spoken and I respect that decision," he said. As his wife cried by his side, Castle said they had a long discussion about whether he should run run for Senate, and joked, "We'll have another discussion tonight about whether that was the right decision."

But the Castle loss was no laughing matter for national Republicans, who had heavily backed the moderate congressman throughout his candidacy. State Republicans had also pushed Castle strongly over O'Donnell, with party Chairman Tom Ross once warning that O'Donnell "could not be elected dog catcher."

On Tuesday night, the National Republican Senatorial Committee put out a terse, one-sentence statement only congratulating O'Donnell on "a hard-fought campaign." Sources also indicated that the NRSC would not help O'Donnell fund her campaign in the fall.

Democrats, meanwhile, were thrilled with the O'Donnell victory, since they had been eager to face her instead of Castle in November. While O'Donnell is popular with conservative Republicans, the congressman had wide, bi-partisan appeal in the state where Democrats and independents outnumber Republicans 2-to-1.

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A Public Policy Poll taken over the weekend showed Chris Coons, the New Castle County executive and Democratic nominee, 26 points ahead of O'Donnell in a head-to-head match-up.

DNC chairman Tim Kaine said the O'Donnell victory is a sign of things to come for the GOP. "Today the Republican Party has shown just how far right it has moved."

In the weeks leading up to the election, O'Donnell rose steadily in the polls even as she endured a stream of withering attacks from fellow Republicans, including a Castle campaign radio ad that called her "a financial nightmare" because of her problematic personal finances, including a law suit filed by her college for $4,000 in unpaid tuition nearly 20 years after she graduated.

She responded to the ad on CBS News saying she had learned from her mistakes. "Of course in this economy I've fallen on hard times," she said. "But I worked hard. I sacrificed. I made the decision that I needed to make things right."

Over the weekend, O'Donnell's former campaign manager recorded a robocall for the Delaware Republican Party accusing her of using campaign funds to pay her rent and personal expenses while failing to pay staffers' salaries and of being a "professional candidate." O'Donnell has run for the Senate two times before, including once against then-Sen. Joe Biden.

Beyond the internal GOP fire, O'Donnell also took plenty of heat from media across the political spectrum. As MSNBC ran old footage of her denouncing masturbation in the 1990s, the conservative Weekly Standard reported on the details of a law suit O'Donnell filed against a former employer, alleging sexual discrimination and asking for nearly $7 million for "mental anguish" after she was fired from her job.

With so much noise surrounding her candidacy, GOP guru Karl Rove predicted Tuesday night what Democrats are hoping for: that O'Donnell will lose the general election in November when Democratic and independent voters get into the voting booths. "There's just a lot of nutty things she's been saying," Rove said in an appearance on Fox News. "This is not a race we're going to be able to win."

Castle is now the eighth candidate favored by the national Republican Party establishment to fall in a Senate primary this year. More conservative insurgents also knocked off moderates in Florida, Nevada, Kentucky and Colorado and incumbents in Utah, Alaska and Pennsylvania.

Senate Minority Leader Mitch McConnell, who has backed all of the nominees to go down so far, downplayed the turmoil in his party in an interview with NBC News on Tuesday. "We'll get behind the nominees of the party," he said. "I'm confident I'll be the leader of a larger group than I am right now."

With chants of "Yes we can!" filling up the Dover, Delaware ballroom where she held her victory party, O'Donnell thanked Sarah Palin and the Tea Party groups that helped elect her and promised to unite with Republicans in Washington.

But she added, "Don't underestimate the power of 'we the people.'"