O'Donnell's primary victory is a win for . . . the White House?

Of all the primaries so far this year, none has been sweeter for the White House than the one in Delaware on Tuesday night.

Christine O'Donnell's stunning victory in the Republican Senate primary  changes the subject - at least for now - from the troubled national economy to the fractured Republican party. It also puts the seat once held by Vice President Biden back in play for the Democrats, which in turn reduces the odds they will lose control of the Senate.

The Obama administration is uniquely bound up in this small state: Biden represented it for more than three decades, and when he left, his son, Delaware Attorney General Beau Biden, entertained the idea of running to replace him. His decision not to do so created a vulnerability for Democrats, because it was widely assumed that moderate Republican Rep. Mike Castle would have the edge in whatever race emerged.

White House communications director Dan Pfeiffer and 2008 campaign manager David Plouffe are also natives of the state, which Obama won in the Democratic primary (54 percent to 42 percent against then-Sen. Hillary Rodham Clinton) and in the general election (62 percent to 37 percent against Republican Sen. John McCain).

On Wednesday morning, after Castle lost and the Republican establishment was set reeling, White House officials were ecstatic about the turn of events.

"Until last night, the Republicans were counting on Delaware. Not anymore," Pfeiffer said, adding that when the seat first came open, "no one could envision Mike Castle losing."

Best of all, from the administration's perspective, are the conservative social views O'Donnell has promoted during her repeated attempts at political office. "The energy in the Republican party is now centered around a series of policies that are anathema to most voters, including abolishing Social Security and Medicare and eliminating the Department of Education," Pfeiffer said. "These are the Republican candidates. And now these are the Republican positions, and they must defend them."

At the White House briefing, press secretary Robert Gibbs tried to repress a smile when the subject of the Delaware race arose.

"Last night showed that there's a very vociferous debate going on inside the Republican Party for the hearts and minds of Republican voters," Gibbs said. "I think if you look at what people like Karl Rove, what people like the GOP state chairman, have said, the Republicans in Delaware have nominated someone they don't think could win." At a different point in the briefing, answering an unrelated question on tax policy, Gibbs cheerfully volunteered that the "Republican party appears to have differing viewpoints on a whole host of issues."

Kevin Madden, a Republican strategist, warned Democrats against making too much of O'Donnell's victory. But he did so without praising her.

"The White House should still be very wary," Madden said. "The Republican turnout was indicative of a hyper-energized conservative base. It also indicates just how prominently spending issues and big government sentiments are figuring into the mobilization of voters right now. The midterms are still a referendum on the guys in power and, wow, are voters ticked off at the guys in power."