I have a few doubts about the electoral applicability of comparisons between Scott Brown and Christine O'Donnell. Yes, they're both outsiders with gumption (or so we're told), but the challenge Scott Brown faced in Massachusetts in January is quite different from the one that O'Donnell faces in Delaware in November.
It's true that Brown was considered a long-shot candidate, but take a look at his favorability rating in this early January 2010 Boston Globe poll (which showed him trailing Democrat Martha Coakley by 15 points): 44% favorable/25% unfavorable, with 23% who were uncertain. That's a +19 net favorability rating. Brown's public image was mostly positive; he needed to prove his competitiveness and to become a more familiar presence to voters.
Take a look at O'Donnell's numbers from some recent polls. Fox News: 33% of Delaware voters view her to be qualified to serve as senator while 60% think she's unqualified. That's a -27 net rating. PPP: 29% favorable / 50% unfavorable. -21 net rating.
To point out these statistics is not to talk down O'Donnell's chances in the general election but to note that she has a very different strategic imperative. While voters in Massachusetts were generally favorable and open to Brown, a majority of Delaware voters are actively hostile to O'Donnell. Opinion is not unformed about her (as in Brown's case) but instead has soured against her candidacy.
O'Donnell will need to fight to reverse the media narrative that's grown up around her. Outreach---to Castle's people, to independents, to the media---is going to be crucial.
With that in mind, one might have a few misgivings about her decision to avoid any national television interviews for the rest of the campaign. The 2008 election is instructive in this regard. By mostly keeping Palin in a media bubble after her debut as vice-presidential candidate, the McCain camp indirectly helped solidify Palin's image as a Tina Fey "I can see Russia from my house" caricature. It's understandable for the O'Donnell team to want to avoid a media feeding frenzy, but her campaign should be wary of a similar fate befalling her.
Her campaign has suggested that O'Donnell's going to be pursuing local new organizations. She should be. She should also be getting out there with the voters (which she seems to be doing)---even in less-than-friendly territory. O'Donnell's accumulated something like a $2 million war chest. That spending should help, too, but blanketing the airwaves with advertisements will only do so much good. For O'Donnell to win in Delaware, she will need voters to view her as more than a "conservative" firebrand.
As William Jacobson says, it might be to early to count O'Donnell out of the race. But she does have a lot of work to do, and there are plenty of other Senate races for those on the right to keep an eye on.