An upset in Delaware?

With two-thirds of the vote counted, Christine O’Donnell leads Mike Castle by almost 10 percentage points in the Senate primary. Unless the remaining vote is heavily skewed towards Castle precincts, O’Donnell obviously is looking very strong.
In light of recent polling, an O’Donnell win wouldn’t be surprising. But considering where she started in the race, I certainly think such a win would be an upset.
UPDATE: The race has been called for O’Donnell. She wins by 7 percentage points [make that 6 points]..
The result represents a victory for the Tea Party Express and Sarah Palin. But I believe the big winner is Chris Coons, the Democrat, whom I expect to defeat O’Donnell handily in November, as Joe Biden defeated her last time.
Meanwhile, Beau Biden must be wishing he had run this year. It’s generally believed that Castle scared him off.
It’s disappointing to squander an opportunity to pick up a Senate seat. But it will not be tragic for Republicans (or a “nightmare,” to use Politico’s description) unless it costs Republicans control of the Senate, and that’s unlikely.
How unlikely? Nate Silver, who crunches numbers and has a good track record, estimates that O’Donnell’s nomination lowers Republican chances of gaining control of the Senate from 30 percent to 21 percent (if the Republicans nominate Kelly Ayotte in New Hampshire) and from 23 percent to 16 percent (if the Republicans nominate Ovide Lamontagne instead of Ayotte).
Lamontagne leads Ayotte in New Hampshire in the early results. If that result holds, then according to Silver’s model, Republican chances of capturing control of the Senate will have dropped in one night from 30 percent, in an optimal scenario, to 16 percent.
However, in my view Silver’s model has too many moving parts to put much stock in. It is clear to me that O’Donnell’s victory lowers the odds of Republicans taking control of the Senate, but by how much I have no precise idea.
SECOND UPDATE: There’s another possible nightmare scenario associated with O’Donnell’s victory: Coons is elected and during the lame duck session casts the 60th vote for an awful piece of legislation that Castle has opposed. But I think this possibility is remote.
JOHN adds: It is worth noting that the Tea Party movement flexed its muscles in New York, too, where businessman Carl Paladino beat Rick Lazio, who ran against Hillary Clinton a few years ago, for the GOP gubernatorial nomination. Lazio is, as far as I know, a solid conservative–I think he is the only New York politician to whose campaign I have ever donated–but Paladino was the upstart Tea Party guy. It probably won’t matter, as either Lazio or Paladino would be a prohibitive underdog against Andrew Cuomo in November. Still, it is one more sign that 2010 is the Year of the Tea Party.