The Delaware campaign, which had been sedate, became in its latter days a vicious battle in the ongoing war between the establishment and tea party insurgents that has marked the 2010 GOP primary season.
Activists were energized after Joe Miller, a tea party movement candidate, knocked off Sen. Lisa Murkowski in Alaska's Republican primary Aug. 24. Miller believes Social Security and Medicare should end and has called unemployment benefits unconstitutional. He also stands a good chance of winning the seat, polls show.
Murkowski and her party allies did not take Miller seriously, and she was ambushed. The Delaware GOP was determined not to repeat the mistake, and unleashed a barrage of attacks on O'Donnell's character that continued Tuesday as voters went to the polls.
O'Donnell, a perennial candidate who was the GOP's nominee two years ago against Biden, has had financial problems, including unpaid debts to her college, a federal tax lien (since satisfied), and difficulty paying her mortgage. She declared that GOP spies were stalking her, and once filed suit against a conservative non-profit for sexual harassment, in which she falsely claimed she was taking master's degree classes at Princeton University. Castle supporters used them all to impugn O'Donnell.
These attacks only solidified O'Donnell's fervent grassroots support.
"It really is a struggle for the soul of the Republican Party, whether it will be controlled by the establishment or common-sense conservatives," said Kristen Sherman of Bear, Del., events coordinator of Founders' Values, a limited-government group allied with tea party organizations. "Mike Castle has taken the mentality that he's entitled to the position, that he doesn't do 'job interviews.'"
Former Alaska Gov. Sarah Palin, the GOP's 2008 vice-presidential nominee, backed O'Donnell, as did Sen. Jim DeMint (R.,SC), a leader of the right. But Freedom Works, an advocacy group that helped spark the tea-party movement, stayed on the sidelines, believing that O'Donnell could not win in the general election.
In addition to Alaska, tea party backed candidates won the Republican nominations for Senate in Utah, Nevada and Kentucky. Polls show all of them could win.
Delaware's electorate, however, is traditionally moderate, and Castle, 71, argued that O'Donnell would be unelectable in November.
On Tuesday, the state GOP was using a robo-call with a recording by a former O'Donnell aide who said the candidate had used campaign donations for rent and other personal expenses.
"She wasn't concerned about conservative causes, O'Donnell just wants to make a buck," Kristin Murray, her 2008 campaign manager, says in the recording, first reported by Politico.
Tea party activists are angry about Castle's votes in favor of the bank and auto bailouts and the stimulus program, and especially for the Democrats' energy bill that would impose a cap-and-trade system for reducing carbon emissions. Opponents of that approach say it amounts to a tax that will drive up the cost of energy.
Though Castle voted against the national health-care legislation, conservatives were not impressed, because he has declined to support an effort to repeal the plan.
Political insurgencies face less resistance in small states like Delaware, especially in this angry climate. Only a relative handful of the state's Republicans will decide the Senate primary. On the edges of the Philadelphia media market, candidates can win primaries by knocking on doors and going to festivals, and ideologically driven voters tend to show up more often in primaries than moderates; the state GOP is also divided by factions.
Castle needed a good turnout from populous New Castle County, the northernmost of Delaware's three counties, home to many moderate Republicans. Rural Kent and Sussex Counties tend to have more conservative GOP voters.
The liberal Americans for Democratic Action last year rated Castle the most liberal Republican in the House, saying he voted in line with the group's views 55 percent of the time. He also voted 56 percent of the time with the American Conservative Union.
Castle is pretty much in line with other Northeastern Republicans in the House who have moderate voting records, including Reps. Charlie Dent, Jim Gerlach and Todd Platts of Pennsylvania; Leonard Lance and Frank LoBiondo of New Jersey; and Peter King of New York.
It used to be a bigger group. Northeastern moderate Republicans have become a threatened species, felled in by conservatives who want to purge the party of "RINOs," - Republicans in name only - and by the the Democratic sweeps of 2006 and 2008.
Nonetheless, Castle goes down well in Delaware, which has a long tradition of moderate and personal politics. People still talk about how he would dress up on Halloween to pass out candy at the governor's mansion, or about seeing him in a local parades, for instance. Castle was reelected to the House with 61 percent of the vote in 2008, a Democratic year with President Obama and Biden at the top of the ticket.
Contact staff writer Thomas Fitzgerald at 215-854-2718 or firstname.lastname@example.org.