The battle for Delaware's Republican Senate candidacy is heating up, with Tea Party favorite Christine O'Donnell squaring off against GOP establishment choice Mike Castle. Polls give Castle an edge over O'Donnell ahead of the Sept. 14 primary, but the Tea Party Express has thrown its considerable support behind O'Donnell, a Christian conservative, pledging $250,000 to air ads on her behalf. Castle has responded by stepping up attacks on his opponent and devoting a website to her many gaffes. Can O'Donnell follow in the footsteps of Alaska's Joe Miller and pull off another Tea Party upset? (Watch The Week's Sunday Talk Show Briefing about Republicans' chances in the midterms)

With the Tea Party involved anything could happen: O'Donnell has a closet full of skeletons, says Chris Good at The Atlantic, and would ordinarily seem like an outside bet against a tried and tested candidate like Castle. But the involvement of the Tea Party Express — which powered Joe Miller to victory in Alaska — changes everything. Call it the "Tea Party Express Uncertainty Principle." Once the Express get involved, "all bets are off."
"Bad stuff 'bout Christine O'Donnell"

O'Donnell poses a threat, so the GOP will shut her down: Unfortunately for O'Donnell, says David Weigel at Slate, the GOP attack machine is out in full force. She "poses a threat to an easy GOP win in Delaware, so out come the guns." In recent days she has been "whipsawed" by attacks from Castle's campaign team, and it's not yet apparent she has what it takes to "survive the onslaught."
"Christine O'Donnell vs Christine O'Donnell"

Dirty tricks mean she doesn't deserve grassroots support: I'd much rather see O'Donnell win than Castle, says Erick Erickson at RedState. But her campaign has been playing some dirty tricks of its own — specifically, spreading baseless rumors that Mike Castle is having a gay affair. This is "amateur hour" stuff and helps neither O'Donnell nor the Tea Party. Her failure to shut it down means she's lost my support.
"Pulling the plug in Delaware"