[9] After her 2008 loss to Biden, Christine O'Donnell had indicated she would strongly consider running for the seat again in 2010, asking supporters on her website to "save your yard sign!!

[13] In her remarks, O'Donnell criticized excessive government spending, said that Castle was the most liberal Republican in the House, and said that the Tea Party movement and grassroots anti-incumbent trends would be in her favor.

[14][15] When a report from The News Journal in March 2010 detailed O'Donnell's fiscal difficulties, she attributed the problems to misunderstandings and errors, and said, "I think the fact that I have struggled financially is what makes me so sympathetic.

[19] A July 2010 Rasmussen Reports poll showed O'Donnell running ahead of Democratic Senate candidate Chris Coons by a margin of 41 to 39 percent in a hypothetical matchup.

[20] During this time she picked up the endorsements of the Susan B. Anthony List, the Tea Party Express, which called her a "strong voice for conservative constitutionalist principles",[21] and the Family Research Council.

[22] O'Donnell supporters were heartened by the late August primary victory in Alaska of little-known, Tea Party-backed insurgent Joe Miller over incumbent Republican Senator Lisa Murkowski.

[19] The added buzz about her campaign and the possibility that another establishment Republican figure might be defeated by an insurgent brought national attention to the race.

[24][25] As September began, the tone of the race grew nastier, with Delaware Republican Party chair Tom Ross saying, "Is Christine O'Donnell actually this unhinged from reality?

Or is she simply a liar, whose total lack of respect for Delaware voters leads her to deliberately and repeatedly deny the clear facts surrounding her many personal and professional failures?

[29] O'Donnell later appeared on Mark Levin's radio show, where she blasted Castle's "unmanly tactics" during the campaign, saying, "this is not a bake-off, put your man-pants on.

As O'Donnell's manager, I found out she was living on campaign donations - using them for rent and personal expenses, while leaving her workers unpaid and piling up thousands in debt.

[33] A few days later, The Weekly Standard broke new details of O'Donnell's 2005 $6.95 million gender discrimination and wrongful termination lawsuit against her former employer, the conservative Intercollegiate Studies Institute.

[35][40][41] O'Donnell was considered far less electable in a general election than Castle; Politico reported, "The path to a Republican Senate takeover narrowed to the point of vanishing Tuesday night, as marketing consultant Christine O’Donnell upset Rep. Mike Castle in Delaware’s Senate primary and likely dashed the GOP’s hopes of capturing the seat in the process".

[43] Former Lieutenant Governor John Carney[44] and State Attorney General Beau Biden,[45] both Democrats, opted not to seek the Senate seat, either.

[46] The National Republican Senatorial Committee similarly released a statement almost immediately following O'Donnell's primary win, stating that they would not spend money to support her or her campaign.

[90] For her own part, O'Donnell criticized divisions within the Delaware Republican Party following her primary win and said the consequent lack of support had led to her defeat.